The information from the lads above is all good.
First you need to decide why you want a rifle. i.e. target, vermin control, deerstalking etc
Target - You will need to join a club, and you will be limited to shooting at a club.
Vermin Control - You will need to have written permission for vermin control on ground that is suitable for the caliber of rifle that you want.
Deerstalking - Ideally you will want to have written permission for deerstalking on ground that holds deer. It is possible to have a deer caliber rifle without have permission, if you book paid days stalking, you would need to have receipts and letters from the stalker/estate. Also, it is likely that you will be pushed to get your DSC1 (Deer Stalking Cert level 1) before being granted a deer caliber from scratch.
It's all about proving 'good reason', if you can prove 'good reason' then you shouldn't have any problems.
Another thing that is becoming more common is to make new FAC holders have a mentor for a period of time, if you have this lined up
before you apply it may also help your case.