If you already have a PC why not just run the bots on that then get a laptop to do whatever that is you need to do? If you haven't actually started botting, I guess the best bet is to buy a PC dedicated to handling those 4 bots (wouldn't cost much, look up how to reduce gfx and resolution further than is allowed by the in-game options) then get a laptop for your school needs. 4 bots can get quite heavy for a laptop, considering you'll probably be doing other things on it while it's running.