A few comments:
1) an older boat that might have a fair number of fittings of UK origin may be more difficult to maintain than a newer, more common boat.
2) Assuming you are in Fl, as indicated: The shallow draft of a twin keel boat is a benefit most of the time, but if you do go aground it can be harder to get off since you can't reduce draft by heeling the boat.
3) Boats designed for breezy UK conditions have small sail plans for US conditions, and my be a little dull. (My impression is the Florida sailing is calm interupted by thunderstorms.) A boat with sluggish handling is harder for a beginner than one that respondes to every twitch.
4) My suggestion is a locally popular boat that is easy to sell, since your interests will change as you learn, and you will want something different pretty soon, no matter what you start with.
