tasum wrote:I was thinking of chopping the barrel down to make it more handy for practical shotgun, but I'm not sure how much I can chop off and what the shot pattern will be like without a choke.
A cylinder bore will open up patterns, but not to the point of complete uselessness. It'll depend on the load and what kind of shooting you're doing, of course, but a cylinder bore will work just fine for a lot of things. If you want this to be a recreational gun now and possibly a competition gun in the future, a cylinder bore should be fine. As I understand it, you'll want to have interchangeable chokes on a competition gun anyway. You can always have a gunsmith thread your barrel for choke tubes in the future, even if it's been cut down.
tasum wrote:I will decide on either the 12 or 14 inch hogue stock to determine the overall length as we're restricted to 40 inches minimum and so the stock length will dictate how short the barrel can be.
Are you sure the overall length is the only restriction? Here in the US, we have two minimums: an overall length of 26 inches, and a barrel length of 18 inches (we can legally go below these values, but it requires some additional paperwork, taxes, and other red tape). Before you do anything, make sure you understand your local laws; they should be available online somewhere, perhaps some other UK members can point you to them.
One thing I suggest to those who are shortening their barrels themselves, both for the UK and the US, is to give yourself an extra half-inch or so of padding. For example, I recommend that US shotgun owners cut their barrels to 18.5 inches instead of the legal minimum of 18 inches. If you buy a gun that comes from the factory with a minimum-length barrel, you can at least point to that in the event of a measurement dispute. If you cut your barrel down yourself to the absolute minimum, and there's a dispute about its legality, you really don't have a leg to stand on.
tasum wrote:Anyone any views on the 12 v 14 hogue debate? I'm short at 5'6" so can anyone guide me as to how to measure myself to work out which would be better?
Your best bet would be to try them yourself. Fit is a very personal thing that depends on technique and preference as well as anthropometry.