Probably won't do you much good. Largemouth black bass need warmer conditions than I think they would find in the UK.
Smallmouth black bass, OTOH, do nicely in cooler conditions and the climate there would be fine for them. Very similar fish but doesn't grow quite as large.
Smallmouth will need fairly clear water with some rocky areas if they are to thrive and breed though.
(edit note: to sorta clarify the size thing, a national Bass magazine publishes pics of large bass caught and released alive by any member angler. The minimum for largemouth is 10lbs and the minimum for smallmouth is 6lbs).