Hi GT, To your first question Yes the British left lots of stuff and when I was a boy in the scouts we used to buy ex army stuff for our camping and climbing etc. Now it is not so easy to find anything, it is a long time since the British left, it was in March 31, 1979.
For a small island like ours you be amazed how many guns there are, mostly are inherted from family to family, some keep them for decoration, others are collectors like me, mostly we buy from people that inherted some guns but does not want to keep them. The main source is to buy from abroad through internet acutions or as I sometimes do, go to Germay, Kassel fair and buy from there.
We are not bad with our laws, regard collecting as long as you have a collector licence you can buy anthing as long as it is pre 1946, even full auto
For target shooting we are allowed 10 modern guns to shoot, any caliber.
Regards.
Alf