In reply to Pesda potato:
I did a total career change from civil servant (middle management/policy role) to optometrist. Absolutely the best thing I ever did.
This is probably not a helpful story as the circs were quite different. There were voluntary redundancy packages being offered, and when the rules were such that I got a decent amount, I took it and went back to university full time for 3 years. Then did another year's professional training on minimum wage. All this obviously cost me an arm and a leg (redundancy + savings + loans) but it was OK because I'm single and own my home on a cheap mortgage. I also don't mind being skint, renting out a room in my flat, etc.
So it was pretty easy for me, but on the other hand I chose a "back to the start" option. Being a "full time" (haha) student in my 30s was fantastic and I got a lot of climbing done including many of my dream routes around the UK. But now I have a job I enjoy, and can work fewer hours, don't take work home and can work wherever I like in the country employed or self-employed (or do more quals and go abroad).
But as I say, I really enjoyed the whole process. Going from directionless job-loathing to being on a very specific path to a new profession gave me a completely new outlook, from a bleak future to an exciting one. There are obviously problems with my new profession, but it's the career I chose from a mature and practical standpoint at age 30-odd - and most of the time it's a really nice, fun, interesting job with loads of opportunities in many different directions.