advice for US-based couple renting a car for two weeks in UK in September

Just in case anyone here has given such advice before to US-based family or friends needing to rent a car in the UK:

My wife and I have fully refundable reservations  for a trip to the UK in September. She's dual UK/US citizen, and I'm a US citizen.

We'll need a car for about two weeks. Only my wife will drive. We both have only US driver licenses (her UK one expired and could not be renewed -- she's been here in the US too long). And we live in the US.

In the past few years she has had some trouble renting cars in the UK with her US driver's license.

Here in the US I think I can use  Autoslash to find deals, but I have not pulled the trigger yet.

Good to book a fully refundable car soon since there is not much availability.

Thanks!

We used Europcar several times. If memory serves, they connected us with Alamo at the airports. No problems at all, and good rates.

We used Europcar several times. If memory serves, they connected us with Alamo at the airports. No problems at all, and good rates.

Same here. Last time we did it, in 2016, we used Enterprise.