So, as I understand it,
(scratching head with perplexed expression on face)
real guns (except handguns) can be used anywhere where it would be legal to use them including defense at home IF it was proportionate to the threat, but you can’t own handguns except for muzzleloaders and antiques, unless you deal in them abroad say, or you are a vet requiring them for humane destruction of animals. You can’t carry a gun for defence with some exceptions: probably current and former govt employees in Northern Ireland who have PPW licences. Correct regarding the other 2 points.
This should be informative regarding laws concerning private firearms ownership in the UK today (official as it gets IMO) given that its produced for the London Metropolitan Police themselves:
http://www.met.police.uk/firearms-enquiries/
You may read things such as the govt praising the shooting sports: its BS - if anything, things are becoming more restrictive for those already in the sport and they’re making it harder & harder to start.