All of the UK already has a well defines local Government system, so why not define constituencies by County (which have many traditional and practical identifiers) and only combine Counties where a low population would result in a constituency having less that (say) 3 seats.  Effectively that used to be the case in Ireland, although boundaries have been mucked about since.  Cities could be subdivided into more than one constituency where they exceed (say) 5 seats to retain some level of local identification with candidates.  The larger the constituency, the more it favours larger nationally organised parties over local or single issue candidates with lesser funding/organisation.

Frank's Home Page and Diary Index