Awesome Tabris, good luck man. The best advice I can give having done the same a few times:
- Trust your gut. If the flat *feels* nice when you step in, don't overrationalize it. I turned down an exact same size flat in our house that was 100k cheaper because it just didn't feel somehow as spacious and nice as the more expensive one, and the view wasn't quite as pleasing. Now the price difference is almost 300k to our benefit.
- Decide on the layout, not the condition. That floorplan looks solid. I would not pay too much attention to kitchen styling, bathroom styling, flooring etc. as long as the layout is good. You can upgrade everything else over time but not the layout.
- Whatever your build cost and time is, add 50% on top as a contingency. Chances are it will come handy.
- Plan, plan, plan, document. Our remodel document we made was some 30 pages, every last detail specced out with examples, mood boards and elevations drawn in Illustrator.
- Build in double the storage you think you need. We used evry possible slot and corner for sliding door wardrobes and even extended kitchen cupboards all the way to the ceiling.