For non BP, Pyrodex and triple 7 are readily available in the UK. Pyro is made from BP modified so that it is classed as a propellant rather than an explosive, my view is that it is messier than BP. 777 is a modern substitute very similar to a nitro powder and cleans with just water. Neither need the paperwork or storage box required for BP, I order mine over the phone and get it in the post next day. Yes BP is cheaper but a bottle is likely to last you six months so do you quibble at £35?
The Italian guns are all much the same, the older Pietta were considered a better build though one I have is a right dog. The Ruger is by far the best IMHO but they stopped making it.
“If a cricketer, for instance, suddenly decided to go into a school and batter a lot of people to death with a cricket bat, which he could do very easily, I mean, are you going to ban cricket bats?” :- Prince Philip said after Dunblane