Check that they will let you stay longer with drains in, I know my hospital like to get you out asap to clear beds and I could not have stayed in unless there was a problem. It's really not that bad. You won't need too much help you and should still have mobility but you should not lift or strain for a while. Staying with a relative after will be good for your confidence knowing someone is there. As for the drains you will not have to touch it the district nurse came out to me to deal with stuff and change the dressing etc. They will show you what to do. Once home you can always come here for advice on what to do with them.
As for what to take in (remembering what you take in is what you have to take home). Hopefully you will have someone to carry a bag for you as you will not be able to carry anything too heavy. I would say deinitely long trousers or tracksuit bottoms or long skirt for going home as you will have long socks on that have to stay on at home for couple of weeks ('cos of thrombosis risk). I went in with 3/4 length jeans on and had to leave in pj bottoms as it would have looked ridiculous with white tights on!
Normal underware and spare knickers, I've a couple of vest tops with breast support bit inside which are more gentle than a bra. No bras with bones / wires or lacey bits as these can all irritate. I always pack too much, face wipes, wet wipes, tissues, usual toiletries, I also use the alcohol hand soap and have one on me all the time. Take your own small towel as well, at least you know where it's been. Also don't forget to take any medications you are on with you. Whilst in there they should offer medication for any discomfort. I was lucky and did not need any post op. Hope that's helpful. Every little thing helps and will make you feel in control. I also had a little toilet bag with essentials for going to the loo. Also write a list, that always helps. Don't forget your phone and a charger, and a book to take up some time, an MP3 player if you've got one (you've obviously spent loads of time waiting around going through chemo so probably know all those little bits).
Anything else just ask.
Take care. Hugs n stuff