Depend how big the hole you want to drill. If more than 10mm diameter, get a corded rotary hammer. Cheaper. But very mafan. Need to pull extension wire and not to mention quite heavy (2 hand operation). If you're gonna climb a ladder to drill, very troublesome. But since you said it just occasional, shouldn't be a problem.

If you go cordless, need those 18v-20v one, very expensive.

If the hole is like 6-10mm just to put those plastic wall plug, a cordless 12v one would do.