I only know my own case, but my university, St Andrews, seemed quite open to mature students. I am 40 (just turned, grumble) and had been out of school for a while. I had no problems with the applications here. I did have some trouble applying to US schools, where they seemed more bothered by my not being in school for a while. Here they actually seemed to like people who have some life experience. I took a couple of course as a non-degree student at the university where I was living before applying, to get back in the swing, to show I could do the work, and to get instructors who could write recommendation letters. I'd suggest looking into something like that if its a possibility for you. Otherwise, go ahead and apply. You might also write to the department and tell them you are interested and ask if they have any advice for older students. And don't be afraid to ask them questions when you are applying.