How hard is it to get into the RSPCA?

http://www.rspca.org.uk/ It really depends on what you would like to do there. There are many areas in the RSPCA where one may work. I strongly suggest you start off by becoming a volunteer, its a great way to learn how the place is run and whats involved in being there. I would also suggest speaking to some one directly from RSPCA I am sure they would be happy to answer all questions you may have