In reply to Mr.Ric:
I worked at a centre in the Peak for 3 summer seasons, and then have no work in the winters (Oct-Mar) generally, and I think that's how it generally goes IME.
It might be possible to scrape enough though if you're lucky and have low living costs/have saved a bit, especially if you maybe nip to Scotland for a month and try and get some work there with your WML. Might also be worth looking at the Sheffield (and other) climbing walls as obviously they work all year.
Once you have done a summer in the Peak and have got to know more people you might have a better chance of picking up work to get you through the next winter.
It's a great place to live! Good luck!