Just do it. I was teaching full time for 6 years, the last 3 as head of department, and decided I had to to get out before I became wedded to a job which had drained me of all passion for my subject. OK, I had some freelance work to see me through any uncertain times, but this was worth less than 20% of my salary as a teacher. When my teacher's salary finished I had a couple of uncertain months (with a mortgage to pay) and although I registered with several temp agencies they found me the sum total of zero work. However, I am now working in a field related to my degree and subject that I love. I am challenged and very busy, but with no stress, earning three times what I earned as a teacher, and I'm still freelancing too. I now have 24 days holiday each year, but don't have any issue with this. Fair exchange. I found my work not through an agency but simply through spending very many hours being proactive looking for something suitable. Many former colleagues thought I was mad to take such a huge risk, and maybe I was, but I believe that the long notice periods required prevent teachers from discovering just what great opportunities there are outside of the classroom.

Good luck. Just do it, and once you've taken that brave deicision, don't just take the next job that comes along. Make space for the right opportunity.