Just as you say egg, it's a frightening weight, at such larger sums, in a very uncertain world.
I probably paid more than I could have right the way through my mortgage. I just wanted as much security on the payments as I could get, so had a couple of longer fixed periods in there. Around that, interest rates fell and stayed low for some decent periods. I bumped a bit about it, but I had the comfort of being safer from sharp rises.
I also had the advantage of a bit of equity going in, which made it liveable, with a bit of headroom. Something, as Turkish said, is so often not an option when to get anything, you're already having to overstretch.