I've done the same as you to two victorian houses (floors, skirting, wall/plaster repairs, faffing, etc. leaving the big stuff to the pros), and converted a van from a panel to camper with:
A 14.4V dewalt drill/driver and an ancient corded drill that cover most bases.
A basic Skil circular saw and a chop saw that have been useful
A cheapish Bosch jigsaw
The usual sanders (cheap detail, orbit and belt sanders - I never used the belt sander much; if you've got a lot of old ceilings/walls to repair, get a half decent orbit sander that your hoover can attach to).
Plus clamps, usual handtools, steamer, glue gun, heat gun, soldering iron and foldable work bench. I bought cheap work benches and regretted that (now on my third, should have just bought a decent one to begin with).
I just picked stuff up as I needed it and stolen other bits from my dad, so nothing matches, some is pretty old etc., but the outlay has been pretty small. I like the look of some of those 18V kits, but the 14.4V drill is relatively light (which is useful in awkward spaces, which most spaces seem to be) and does ok until you get to masonry.