We have a smattering when the enthusiastic have started them but it's patchy.

Naming conventions: use your best judgement but go with what makes it easiest for people to find - if there's more than one name go with the English for now and you can save the, for example, Welsh one for a Welsh-language community.

edit: as discussed in the comments, you may be better off with a more regional community first - those like London, Manchester and Liverpool already function like that as they cover the greater city area. So instead of Chelmsford and Southend, start one Essex; instead of Lancaster, start one for Lancashire. At least initially until things really get going here. That list is over here.

The list:

• Aberdeen
• Armagh
• Bangor, Northern Ireland
• Bangor, Wales
• Bath
• Belfast
• Birmingham
• Bradford
• Brighton and Hove
• Bristol
• Cambridge
• Canterbury
• Cardiff
• Carlisle
• Chelmsford
• Chester
• Chichester
• Colchester
• Coventry
• Derby
• Derry
• Doncaster
• Dundee
• Durham
• Edinburgh
• Ely
• Exeter
• Glasgow
• Gloucester
• Hereford
• Inverness
• Kingston upon Hull
• Lancaster
• Leeds
• Leicester
• Lichfield
• Lincoln
• Lisburn
• Liverpool
• London (technically City of London is one too but let's not split hairs at this point)
• Manchester
• Milton Keynes
• Newcastle upon Tyne
• Newport
• Newry
• Norwich
• Nottingham
• Oxford
• Perth
• Peterborough
• Plymouth
• Portsmouth
• Preston
• Ripon
• Salford
• Salisbury
• Sheffield
• Southampton
• Southend on Sea
• St Albans
• St Asaph
• St Davids
• Stirling
• Stoke-on-Trent
• Sunderland
• Swansea
• Truro
• Wakefield
• Wells
• ~~Westminster~~ - stick to London for now
• Winchester
• Wolverhampton
• Worcester
• Wrexham
• York

edit: adding in links to existing ones