We've done it/still doing it.
Run down Edwardian house, neglected and botched for 50+.
One time HMO and badly converted into 2 flats.
When we moved in amongst other delights that the spiv seller had tried to conceal was a dangerous gas leak and wiring that could have fried us at 20 paces.
We've had the roof fixed, the gas leak fixed, re-wired, extensive woodworm treated.
Luckily my partner is very handy and has done lots of the work himself, and I am handy with design and putting in a shift with fireplace stripping/wallpaper stripping/decorating etc.
We've been in 4 years this summer, and we've done about 2/3 of the work needed. It's relentless but we love the house and want to make it great again.
Big ticket items like a new kitchen/extension will have to be saved up for.
We are lucky in that one of our mates is a carpenter/window fitter who replaced all our sashes/ built alcove units at cost price and my brother in law is also a builder and helped OH fit our new bathroom.
We've lived in it throughout with 2 young kids, it's messy, dirty and chaotic but unless you have lots of money it's just the way it is, and luckily we're quite hardy!