There’s a fairly complex process before obtaining a shotgun licence. Applications, police interviews, background checks and a house inspection to see if you have separate secure locations for the guns and ammunition. You need a reason to own the gun with membership of a gun club most common reason. Alternatively professional reasons to own one can entitle you to a licence, farmers, gamekeepers, pest control etc
Very little of the above is correct for a SG... Its a lengthy process for a shotgun grant but not complex.
20 mins for online application £89
GP Med report £60 (approx) which must be factual, not an opinion on suitability.
Metal gun cabinet fixed to wall £50 to £250.
A shotgun is anything from £150 to £20k plus & 1000 cartridges costs a min £250, clay pigeon users will go through 100 per day.
You need a reference from a professional person inc a company director, so your mate who owns a plumbing business can sign.
No reason to own one has to be given at all, the police might ask verbally nor do you need to be in a gun club.
The Police will inspect the cabinet is firmly fixed to a secure part of the house. shot gun cartridges don't need to be locked away either, just out of sight, unless you have more 10,000... keys for cabinet should be in a key safe or another out of sight place that only you know about.
You have mixed up a shotgun grant with a firearms licence, ie a rifle, firing bullets, these do carry the restrictions you mention.