Hi uniquehybrid
If you are getting a ballst from 1000Blubs.com its going be wire for the usa.
Over seas you have differnt voltage and the plugs are not the same.So I dont think it will work for you.There are grow shops and online shops all over the uk.The watts of the ballast will be the same as the blub.If you have a 400watt ballast you will have to use a 400watt blub ect.I think the cost of the shipping would cost alot more than if you get it from a supplyer in the uk.
Good luck and you are on the right track.