How do I survive a work day without caffeine?

Drink water. A lot of it. It won't replace the caffeine, but it will make the day more bearable.
Maybe ask a coworker if they have any painkillers for the headache.

In the long run, weaning yourself off caffeine and getting enough sleep will make you healthier overall.

Wean yourself off the caffeine addiction.

That's the neat thing, you don't.

Short term?
-Keep hydrated. This one is key.
-Take an OTC painkiller for the headache.
-Splash your face with really cold water a few times and go for a brisk walk during a break/lunch period (when I was in office my lunches were pretty small/quick to eat to maximize doing-anything-else time, YMMV).
-Depends on your working environment, but if you have the ability to do at least some of your work standing, stand.
-If you're crazy drowsy and just need some means to stay conscious until clock out, a rubber band on the wrist can help. If you start to space out/feel your eyes start to close, give it a snap. Not the greatest thing, but a little pain can release some useful endogenous chemicals.
-If anyone has little candies in the office, ask if you can take some. The sugar in well-timed doses can help a little.

Medium term?
-When you get home, pack up some dried tea/tea bags of acceptable quality, and immediately place it in your 'going to work' kit (bag, car, whatever) so you have a stash in case you forget to make a thermos/whatever of tea the following (and subsequent) mornings.
-Go talk to whoever stocks the tea at work and let them know they've expired. They may not drink tea themselves, and if no one else has brought it up they may not know/haven't checked in a while.

Long term?
-Ween yourself off of caffeine. Slowly start swapping out your tea stash with herbal teas with no caffeine content (some are quite tasty), and reduce the amount of caffeine you're inbibing bit by bit until it's 0.
-Work on adjusting your sleep schedule.

Have you put sugar in coffee? I'm very sensitive to bitter, and always had to put quite a bit of sugar in to cancel out the bitterness.

As the other commenter said, painkillers and hydration will help

You can offset the bitterness of the coffee with milk and sugar. If you're getting headaches, it's probably just worth trying to grin and bear the coffee.

Failing that maybe something like Uber eats could do you a grocery delivery to wherever you are with some supplies

For the future, maybe try and drop your consumption a little bit, sounds like you're probably smashing it a bit, and to avoid a similar scenario perhaps keep some caffeine pills in your bag for emergencies

You are likely experiencing drowsiness & headaches because you're not getting enough sleep. Happens to me too when I get less than 7 hours of sleep.

Buy a thermos. Make and bring your own coffee.

Find caffeine pills. No-Doz is a popular one, but the dosage is so high you should only have one in a day.

Time release 100mg pills are your friend, if you don't take too many.

50mg pills are hard to find, but better replace a cup of coffee.

100mg pills that are not slow release or time release hit hard and crash hard, but spread them several hours apart and cut them off at noon, and it will absolutely get you through a sleepy day.

Bring your own tea into the workplace?

Tea bags are fine, but I recently discovered tea resin. It's basically a small block of concentrated tea that you dissolve into hot water. Not quite as good as fresh leaves, but more portable (dozens of servings fit in a tin the size of a USB stick) and very resilient against going bad.

I have a small selection of resins on emergency stash in my work bag, in case the coffee machine at the office is broken.

Have your pressure checked.

Some over the counter painkiller to get rid of the headache if you can.

Just take a shot of the coffee in the morning to avoid the headache. I don't know how bitter it has to be for you to prefer a headache over it.

Chocolate :)

Hot chocolate if they got it. If you are used to hot coffee you may miss the warm feeling you get drinking it.

Two options.

Chocolate covered espresso beans. Taste like M&M's

Manhattan Special Espresso Soda. Diet option is available.

https://www.manhattanspecial.com/

Steal away for a quick nap and/or do some light exercise

Buy some tea bags?

Either have the bitter shit and suffer for a little or don't and suffer longer.

Make your own coffee or try caffeine pills. I had to cut back on coffee for a bit due to some stomach issues and the pills work just fine.

Enough exercise, food, hydration and sleep. Ain't no cheat codes for having energy

Buy a pack of Mio energy?

Caffeine pills also exist. Just be careful to not use too much of it

Others have given some simple suggestions that you should try first, but if this is a recurring issue, you could consider seeking an opinion from a doctor. If you have some untreated, underlying condition holding you back, no amount of healthy living or caffeine is going to improve things in the long run.

For example, it's possible to develop allergies late in life, which could lead to grogginess and headaches.

Headaches and extreme drowsiness suggests caffeine addiction. You may want to consider decreasing your caffeine intake slowly over time. As for working without caffeine, unfortunately, that's a bit more complicated. I assume that you have difficulties with getting up in the morning, hence the need for caffeine. That might then imply that you are simply a night owl. These things are biologically hardwired into your DNA, and while night-owl-ness is known to change as you age, there's genuinely nothing that you can do to make yourself into a morning bird.

You can try dimming the lights after sunset, that might help at least a bit with going to sleep/waking up earlier, which might help lower your need for caffeine

Sleep and proper nutrition. Hell, it could be some underlying medical cause. Get a check-up and do some blood work.

Listen to music, keep your feet moving while working.

Bring your own stash and kettle!

You don’t.

hmm the coffee doesn't sound like it is prepared well for you. you might wanna try a french press, which has a way finer taste!

Cold turkey on caffeine - takes about a week and a half to get over the addiction and you'll be sleepy and have headaches for most of it.

After that you'll be perkier than before and will probably even sleep better (depends on how late your last caffeine intake of the day was before as it mainly works by you feeling sleepy earlier and naturally going to sleep earlier).

You can still take something caffeinated once in a while and you will really notice the effect of it once your body isn't hooked on the stuff (just don't to it too often or your body will go back).

You see it turns out that when you're addicted to caffeine you actually require regular caffeine intakes merely to be at your normal baseline level, and will be below it without the caffeine, whilst for those who are NOT addicted to caffeine taking it actually umps them up above baseline (I once read of a study about it but don't have the link anymore).

If you actually like the taste of coffee and the coffee habit as I do, switch to decaf. If you have hot water at work, buy instant decaf and make from that yourself.

If can't be added getting over the caffeine addiction, do you can use instant coffee instead of instant decaf.

Green tea has as much caffeine as coffee. Could you have sleep apnea ?

Excedrin with caffeine. Won't help with the drowsiness, but should be suffecient to get rid of the withdrawal headache.

Captagon

Taper out, your body and brain will get used it it in about a week or two. If you're like me life will stop having meaning as a side-effect. My longest time away from coffee was 3 months, and my mind did totally not get used to it in that time.

I have no doubt about coffee being a pretty hard (even if benevolent) drug.

How much tea do you usually drink? coffee has quite a lot more caffeine then tea. just slam a small shot of coffee.

Murder

Heroin