Purbeck Brotherhood of Ancients (Bournemouth)
Leeds Wargames Club
Devizes & District Wargames Group
Coppull & Chorley Knights
The following did play Warmaster Ancients, but I dont know if they still do.
Contact Bristol Big 'Uns (Iron Acton)
Ponders End Wargaming Club (Endfield, North London)
Sudbury and District Wargames Club Website