Some questions I need help with.

Probably easy to start off with my stats at the beginning.

169cms tall
56 kilos - slim build

Goal is to gain weight, but I have a few problems.

1. I cant train for about a month because I have kidney stone problems and wont be fixed til then, but can I still use that time to bulk a bit? Feels stupid just wasting a whole month when I can be doing something.
2. I have a hip injury from when I was ten. Radiation scars from cancer and chemotherapy so it doesnt function aswell as it should I am able to twist it almost past 90 degrees to the left and hardly any to the right.

I want to train my legs somewhat because I dont want to be big up top and small down the bottom cos it looks dumb. I may have trouble with doing squats or burpees anything that may put pressure on my hip, it wont last forever so i have to be careful. Apart from that I can do any other sort of weight training it doesnt bother me. I am trying to find out what would be the best exercises for me to do for longevity, and maintaining muscle mass. Being shredded is ok but its not my biggest concern i just want to look healthier and maybe have my *kitten* and arms a lil bit thicker lol. Also I have a family at home so Im open to budget ways of getting my carbs proteins and fats into my system because I need to look after them aswell. Any suggestions would be helpful cheers

Elliott