CC only by strict permit on UK mainland. CC allowed in NI.
Handguns on mainland banned in 1997, not in NI. After Dunblane. Assault rifles banned in NI and all UK in 1988 after Hungerford.
UK mainland does allow small amount of handguns: semi-auto pistols up to .22, some pistols/handguns with permit (566 in Scotland, number for Eng and Wales not known, but they are 10 ten times Scots population, so could be 5000+).
Rifles and shotguns legal.
Any restrictions on ammo or magazine quantities. Or types of action?