I hope the surgery goes well.
I guess how much prep you need to do in the workshop depends a little on how hard you normally have to work to keep things rust free. I can pretty much leave mine to its own devices. Never seen any signs of rust on my machines. Occasionally get a light surface corrosion on clean steel stock but generally that’s from sweaty hands. If the shop is closed up and dry it will probably look after itself better than if you are in and out breathing all that moist breath into it.
I would focus on having a good clear up so it’s all nice and welcoming for when you return. Have a think about what you will want to do when you get back to it so you have something to look forward to and everything is to hand.
I don’t know what your surgery is but if lifting is going to be an issue for a while get everything heavy stowed away or where you want it while you can.
Apart from that a general wipe over with the oily rag, lubricate your machines and bring anything really precious into the house.
I think you will find stuff will suggest itself to you as you tidy up.
Just my thoughts really.
Anyway as I say the best of luck with the surgery and I wish you a good and speedy recovery.
Best Wishes Martin