>>Enterprise has a pickup point at Oxford airport <<

Good to know.

>>Do we need a car in Bath (we are driving to Bath for 2 nights after the Cotswolds), or should we return the car as soon as we reach Bath, and find another way to get to Heathrow for our return journey? <<

You don't at all need a car IN Bath. So if you are spending the basically 1.5 days there after leaving the Cotswolds, yes, I'd turn it in. There is a fast, relatively inexpensive National Express coach directly from Bath to LHR so no need to faff about dealing w/ the rental return and shuttle bus at LHR. And ABSOLUTELY no reason to fork over for a car service.

Thanks for the tip janisj. I have just reserved seats on the National Express coach. Much cheaper than private driver and very convenient. Much appreciated.

" be brave and use public transport. "

What on earth is brave about travelling the way everyone else does?