I'm thinking of applying for a shotgun certificate, any tips?

I am 14, and have belonged to a rifle club for a year approximately now. I have always contemplated since, whether or whether not to get a shotgun certificate. A few months ago, I decided I was going to, and I am aware of all the precautions and laws on these things. I am a full member, as I said, and no one in my club has any evident objections to me getting a shotgun certificate. I have had no convictions, and haven't been in ANY trouble from the police as long as I can remember. I am not going to get one till next year, but I'd like to try clay pigeon way before I decide to apply for a shotgun certificate, just to confirm to myself that buying a shotgun won't be a waste of time. I live in a 3 bedroom house, made with brick and concrete in places. I am fortunate enough to have a set of cupboards in my bedroom, where I can bolt, and drill the shotgun safe/cabinet into the wall. I know that the ammunition has to be stored in a separate space above the actual compartment where the shotgun is going to be kept. Tim, a man in a local gun shop near me said that a good 12 gauge second hand shotgun would cost anything from �250-�700. Any other tips, thanks.