I would second Alice (soldiercrab's) suggestion about the pillows.
If money isn't tight I'd buy a cushion like she described- i found sleeping horrible for about 6 weeks also.
make sure you have tops you can pull on without lifting your arms and bottoms you can pull on easily as your arms will be weak (surprisingly no one told me this and I had to do a shop about 2 weeks after!)
You'll be showing lots of people your chest after the operation (Drs and nurses!) so don't wear dresses unless you're happy to strip off each time or they can be pulled down.
Watch out for constipation if you're having lots of pain relief!
There's an app called simply being. It's for meditation and helps with going to sleep. You choose one of the meditations and the background sound and you can set the background sound to continue as long as you like. It may help you with your anxiety about the surgery.