Ravenair are also at barton, not just liverpool. and will have many more opportunities than LAC as also have all the maintaince there.
it would be better to walk in and ask face to face than just phone up. pitch up there at the flying school and ask to speak to martin hatton - he is a very approachable guy.
they have taken on people like you before, if you walk in and offer to clean the planes for free then they'll probably say yes!