I think you'll find buying a smaller home or going on fewer vacations or eating out much less and getting some domestic help will drastically improve the quality of your life.
Or just get a new job in the same city with better pay.
Edit: Oh, I see you're in the UK. That is quite different. Try pointing that out. The UK has several high cost areas and lower cost areas as well, but I know little about the tech scene.
The solution may be "Dude get's higher paying job"
I earn the going rate for a PHP developer in my area, in a job that I love that's close to where I live. Unfortunately it's a fairly low-paying area, so although I could probably squeeze another couple of grand out of a different employer, that would be eaten up by travelling costs/etc.
If money were the issue here, I'd just go up to 5 days a week.
My gut says 'Don't buy this house, it's the wrong size for your income/family situation and in a place that doesn't pay well enough for the life you want.'