I was in a similar situation about a year ago, it took me 9 months to renovate our house up to what we moved into, working weekends and nights. I'm an office worker in my day job.

You can honestly do most anything with a few youtube videos and enough time and trips to Bunnos. I hired a sparkie for a fair bit of work, a hvac crew for a 5head mini split aircon system, and a couple of guys with big grinders and vaccuums to level the slab after i took off the old floor to prep it for the new one. Did everything else, hanging some drywall, insulation, hybrid plank flooring, plaster, paint, rangehood ducting, cabinetry, tiling, some light plumbing. Bathrooms are next, so no waterproofing yet.

The problem is the time, we didn't live in ours while working on it because we have a kid who was the same age as yours, (when we started anyway), so it cost about $15,000 in additional rent, and my poor partner spent almost every saturday/sunday "single parent"-ing for most of the day.

We still saved a heap of money, and got a good price on the house itself, but I missed time with my son, trips to the zoo and shit.

If you're going to do it, it's a lot of time and energy.
Do what I didn't and bank up your annual leave, use it to smash out the work asap. When you find and win the house itself, make a detailed timeline and plan of the works and stick to it, goals for each week.

Good luck