Things to pack
Firstly I would advise taking a wheeled suitcase/bag if possible as it means you don't have to physically carry your bag when you leave. Even if your hospital lets visitors in (I was in April last year and my hospital didn't let visitors in past reception), having a wheeled bag means you don't have to wait for someone to carry your stuff if you're ready to go.
- Loose PJs or nightdress, nightdress is better as you don't have waistbands around your incision sites (just wear loose underwear underneath for if you need to pull it up if anyone needs to check your incisions);
- Dressing gown and slippers - some hospitals have you walk to theatre and you'll want them for walking after the op to get rid of gas pain;
- If you wear glasses, take a glasses case so that when you get to theatre you have somewhere to put them so they don't get damaged when the staff take them to recovery/back to your room;
- Toiletries so you can wash/shower/brush teeth etc;
- A long phone charger or power bank, just in case the outlet isn't close to the bed;
- Something loose and comfortable to wear home, consider slip on shoes so you don't have to bend to do laces/buckles;
- Some form of entertainment - book/magazine/tablet etc. Even if you don't think you'll be up for it post op you may be late on the surgery list so it's good to have a distraction while you wait
- Earplugs/eyemask - even if you have a private room (so no general ward noise/light) you will still have people coming in and out of your room to do observations etc through the night and letting in light from the hall; as well as monitors and machines making noises, so it's good to have a way to block them out, especially if you're a light sleeper.
- A small foldable shopping bag - I was sent home with two massive paper bags full of meds for the first month, including blood thinking injections and a sharps box and they were awkward to try and carry along with my bag, so I was glad I had a reusable shopping bag with me to put everything in to make it easier to carry
Not for the hospital but for the journey home if you're in a car, a pillow to put over your lap to cushion the seatbelt and use to brace if you go over rough roads etc.
Post op prep
I would advise not to pre-prep too much food as I found my tastes changed post op and you can end up wasting things - eg I used to love strawberry and orange flavoured things pre op but now they taste different (not bad, they just don't hit the spot the same); post op it's apple and blackcurrant flavours that I reach for first
What I would advise is stocking up on small sized Tupperware - the "snack size" pots are perfect for the first few stages - so you can portion things into manageable amounts.
If, like me, you don't like milkshakes and so don't like the idea of protein shakes, look into protein water. You can get some ready made ones or buy the protein powder in a tub to add to water, but again don't commit to a big tub of stuff you like preop as your tastes may change so there are options like MyProtein who do a sample pack so you can try all the flavours before committing www.myprotein.com/sports-nutrition/clear-vegan-protein-variety-box/13043239.html (they do a non vegan one, it's just out of stock ATM so I've linked the vegan one so you can see what I mean)
Another tip, stock up on pads/tampons as WLS can often trigger periods. Fat cells store estrogen, as you lose weight rapidly after WLS the fat cells break down and dump a huge amount of estrogen into your system which sends your hormones out of whack and can trigger periods, even if you haven't had them for years due to birth control, and your cycle may not regulate for a few weeks/months so you can get spotting quite a lot in the first few weeks, so better to be prepared!
And finally, as hard as it is, don't compare yourself to other people - everyone will lose at different rates and will stall at different points and it's all perfectly normal so don't panic and trust in the process. As part of that, take measurements and photos! Some weeks I didn't lose weight, or lost maybe a pound or two, but I lost inches everywhere which is something you don't always notice, especially if you're focused on the scales only.