Here is a list of all the counties in the UK, England, Wales, Scotland & Northern Ireland, these should link you to a page with Camper Van Hire Companies in each County. (If there is no link I have not got there yet, hope this helps you find a place to tool up for your next adventure.)
England:
- Bedfordshire
- Berkshire
- Bristol
- Buckinghamshire
- Cambridgeshire
- Cheshire
- Cornwall
- County Durham
- Cumbria
- Derbyshire
- Devon
- Dorset
- East Riding of Yorkshire
- East Sussex
- Essex
- Gloucestershire
- Greater London
- Greater Manchester
- Hampshire
- Herefordshire
- Hertfordshire
- Isle of Wight
- Kent
- Lancashire
- Leicestershire
- Lincolnshire
- Merseyside
- Norfolk
- North Yorkshire
- Northamptonshire
- Northumberland
- Nottinghamshire
- Oxfordshire
- Rutland
- Shropshire
- Somerset
- South Yorkshire
- Staffordshire
- Suffolk
- Surrey
- Tyne and Wear
- Warwickshire
- West Midlands
- West Sussex
- West Yorkshire
- Wiltshire
- Worcestershire
Scotland:
- Aberdeenshire
- Angus
- Argyll and Bute
- Ayrshire
- Banffshire
- Berwickshire
- Borders
- Caithness
- Clackmannanshire
- Dumfries and Galloway
- Dunbartonshire
- Dundee
- East Lothian
- Edinburgh
- Falkirk
- Fife
- Glasgow
- Highland
- Inverclyde
- Kincardineshire
- Lanarkshire
- Midlothian
- Moray
- Orkney
- Perth and Kinross
- Renfrewshire
- Shetland
- Stirlingshire
- West Lothian
- Western Isles
Wales:
- Anglesey
- Blaenau Gwent
- Bridgend
- Caerphilly
- Cardiff
- Carmarthenshire
- Ceredigion
- Conwy
- Denbighshire
- Flintshire
- Gwynedd
- Merthyr Tydfil
- Monmouthshire
- Neath Port Talbot
- Newport
- Pembrokeshire
- Powys
- Rhondda Cynon Taf
- Swansea
- Torfaen
- Vale of Glamorgan
- Wrexham
Northern Ireland:
- Antrim
- Armagh
- Down
- Fermanagh
- Londonderry
- Tyrone