If this is helpful, you can leave your sidecar with me at Motopodd in Weston Turville, it will be looked after, safe and happy!
We are outside the M25, but not by far, NW of London, the postcode is HP225RQ if you want to check.
There is a quick train into London from here, it takes about 45 minutes to Marylebone Station.
We are halfway between London and Oxford, it's a 25 minute ride to Oxford from here.
I can give you a good route to Stonehenge and Sammy Millers, both places I have been to a lot over the years. :)