Purbeck Brotherhood of Ancients (Bournemouth)

Leeds Wargames Club

Devizes & District Wargames Group

Coppull & Chorley Knights

Lancaster Wargamers

Brighton Warlords 

Weston Wargaming

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