Travelling from Scotland to Spain with two dogs

Hi all,

we are planning on travelling from Stirling in Scotland to Southern Spain through France. We intend setting off on 12th January to head for the Eurotunnel as it is quicker for the dogs. Our problem is where to stop on route to let the dogs have a well earned run about. Motorway services seem to have limited areas of grass. We hope to break up the journey by stopping somewhere south of the boarder for an early evening break then heading down overnight to get to the tunnel in the early hours.We will find a site in France a couple of hours from  the tunnel for a good overnight or two then head for Dordogne for a couple of nights then Spain for a couple of months.Any ideas on decent places to stop with our car and caravan to let the "wee" ones out and us stretch our legs, in the UK? thanks, Ed