It's actually not too difficult to buy a shotgun if you want one. You just have to prove that there is a valid reason for wanting one, you're not a nutter and you are able to store it safely and securely. I have been considering getting one myself as I quite like a but of clay shooting.
You don't really have to prove you have a good reason to obtain a shotgun certificate, you do for a firearm certificate.
The police WILL ask you if you have a good reason though.
It's a weird situation, i think I've talked about it before, i have both and the procedure is slightly different for obtaining them.
The general rule of thumb is if you would be granted a firearm cert there's no reason why you wouldn't get a shotgun cert as the firearm cert is harder to obtain the shotgun kinda becomes a given.