Dream house (fixer upper), sanity check and financing?

Hi,

I'm (45M) considering buying a house (north London) which is quite dilapidated and renovating it to our needs. It's in an amazing location and has a lot of potential in terms of our family needs (we're me, my partner 44F and two kids 9 and 12). I'm just toying with the idea currently, but would like to hear people's opinions on this.

We are very lucky to be on the upper side of HENRY, possibly R already. Just shy of £3m net worth, I make about £600-700k a year (RS in FAANG) and my partner makes about £70k. We own a house (worth about £850k) which we like with no mortgage, but it's not in a great location, about 30 minutes walk to the nearest tube, and my son needs to wake early to take a coach to school. Kids go to a good state school and we live a good, relatively simple life, so as one can imagine, we save a lot (fill up pensions, ISAs, JISAs etc. and the rest goes to VWRL basically).

The asking price for the house in question is £1.25m though I suspect there's a chance to buy it for a bit less. I estimate the renovation of a house like this would be around £250k-300k, stamp duty between £60-120k depending if we sell the current house and let's say 20k for the process (planning, solicitor etc.) so that's about £1.6m.

My questions are:

  1. Am I insane to consider this? am I going to regret going into an adventure like this and not saving more money and, say, buying a flat for each child or just having a larger saving pot?

  2. How would you approach financing an endeavor like this? Would you just take a mortgage for the house, sell the old one, and pay cash for the renovation? are there any better ways? is it possible to use the current paid off house somehow?

  3. How do I stress test this? What haven't I thought of? What's the worst case scenario here realistically?

  4. Should I talk to a professional about this? if so, who?

Any advice would be welcome :)

Thanks!

EDIT: many down votes, I understand why - was not trying to humble brag and I know I'm very lucky to be in a situation like this. Thanks to all who responded so far in any case!