We are a family of four and would rather drive off the beaten path, than take the train. Our end destination has to be Portugal due to family. We want to begin in Edinburgh and have 5-6 days to make the trip in December. Any advice or any car rental companies you know of? Thank-you :)
You need to rent separate cars at least for Britain and the Continent. Even then, there's a big drop-off fee to pick up a car in Paris, for instance, and drop it in Portugal. Try www.autoeurope.com to test some prices; they may be shocking. See also articles at http://www.ricksteves.com/travel-tips/transportation.
You'd be looking at two really bad things even using one car in the UK and another on the continent:
. Ten hours of hard, straight-line, non-stop, no-deviation driving on the first leg and twice that on the second.
. Roughly five hundred extra bucks for picking up a car in France and dropping it in Portugal.
The short answer is probably not. First, you are renting a right hand drive car and dropping it off in a left hand driving country. Second, got to get it via the Eurostar or a ferry. Both time consuming and expensive. And, second, have you looked at a map and the distances involved. You are going to spend about five days in the car. And, finally, there is always a weather possibility during the winter in France. Doesn't make any sense at all.