As you are thinking of a 'doer-upper' then I would think like Coastpath, but take good advice about what is possible (both with the house, an your own skills) do your sums and remember to allow a good contingency.
It is worth subscribing to something like Housebuilding & renovation, and even going to their shows / exhibitions.
Our journey to building our own house began many years ago when we needed to move. We looked at a house that was too small and generally awful, dark, no flow etc. and didn't buy, saying ' good job we can afford something better'. Later we became friendly with the people who bought it, and did rather as Coastpath has described. It got us thinking.
Bungalows especially can be ripe for renovating BUT they are often expensive, so you might not have money left for renovating.
Another possibility, depending again on your finances and abilities is to look at the kind of large old house that can be split into 2 flats. You take the downstairs one and sell the upstairs.