As mentioned above, Korpiklanni are fab. They're playing at Leeds Rio's on December 5. I can heartily recommend Tyr from the Faroe Islands as well. Loads of trad melodies but they stick to rock instruments.

Apart from Alestorm, who are quite a good laugh live, and Fintroll, I've only come across one recent British example, The Clan Destined, but they are another Martin Walkyier project. A little heavier than Skyclad but pretty good in its own way.