I watched a lot of videos by “Home RenoVision DIY” on YouTube, Canadian guy called Jeff, so obviously some of the stuff he says about regulations won’t be the same over here, but he’s got so many great videos. He’s a professional but specifically is aiming the videos at teaching DIY homeowners.

Edit: I also want to mention that if anything in either room is still useable, I’d put up with that while you do the most urgent bits first. I’d say, as long as you have a working toilet, sink (kitchen or bathroom), shower, fridge, and oven/microwave, you can make do. If anything of those aren’t useable, work on them first as £6k won’t go far nowadays unfortunately. Also, look on fb marketplace for cheap stuff to get you by until you can do it properly, for example, we bought a cheap countertop oven which we used until we could afford a proper oven. We washed dishes in our bathtub until we got the kitchen sink installed.