There's a target list for a full scale exchange on this site.
http://www.subbrit.org.uk/rsg/featur...dices.htm#app5
It's pretty comprehensive, although note it does date from the late 1960's and doesn't refer to the specific locations of Regional Government Headquarters (RGHQ's, also known as Regional Seat of Government or RSG), it just says that each one would be a likely target. In the 1980's there were eleven RGHQ's as follows:
Scotland:
RGHQ: Cultybraggan, nr Crieff, Tayside
Alternate RGHQ: Kirknewton, nr Edinburgh, Lothian
NE England:
RGHQ: Shipton, North Yorkshire
Alternate RGHQ: Hexham, Northumberland
East Midlands:
RGHQ: Skendleby, nr Spilsby, Lincolnshire
Alternate RGHQ: Loughborough, Leicestershire
East England:
RGHQ: Bawburgh, nr Norwich, Norfolk
Alternate RGHQ: Bedford, Bedfordshire
Greater London:
RGHQ: Kelvedon Hatch, nr Brentwood, Essex
(No alternate)
SE England
RGHQ: Crowborough, nr Crawley, West Sussex
Alternate RGHQ: Basingstoke, Hampshire
SW England
RGHQ: Chilmark, nr Salisbury, Wiltshire
Alternate RGHQ: Bolt Head, nr Salcombe, Devon
Wales
RGHQ: Wrexham, Clwyd
Alternate RGHQ: Brackla, Mid Glamorgan
West Midlands
RGHQ: Swynnerton, nr Stoke on Trent, Staffordshire
Alternate RGHQ: Lawford Heath, nr Rugby, Warwickshire
NW England
RGHQ: Goosenargh, nr Preston, Lancashire
Alternate RGHQ: Hack Green, nr Crewe, Cheshire
Northern Ireland
RGHQ: Ballymena, County Antrim
(No alternate)
There was also a (supposedly secret and unknown to the Soviets) Central Government bunker at Corsham in Wiltshire.
Looking at the list it looks like virtually every significant Royal Navy and Royal Air Force base is targeted although most major Army bases aren't, so you could probably add Aldershot, Salisbury, and Catterick (at least) to the list as well.