You're gonna want to wait until you have time for exercising then. It will take up a lot of time.
Anyway, for the food if you go my way, wait to do this until you can workout:
Eat, eat, eat. Anything and everything. Doesn't even matter what it is. Pizza, fast food, hamburgers, chicken, whatever. Just be eating all the time several times a day. Every hour eat something even if you are full to get into the habit of eating. Trust me, you will start to hate eating lol I consider it to be a chore now.
Don't even worry about what it is you're eating. Eating sucks enough at first to be going with the healthy choices. Start with the stuff you like first to make it a bit easier. If you notice you start to get a gut, then you can switch to the healthier stuff. But most people will not last long at it if they do not train themselves to eat first.
Also search out a mass gainer shake.
As for at home stuff:
- pushups wide and close
- leg raises
- squates
- dips off your bed or a low chair
- get a weight bench
Just google at home workouts