I just browse best deals with the airport rental places and then haggle at the pick up for a better car. Often can get something nicer for little or no extra cost. Especially when you’ve got lots of kit (in my case been group with loads of luggage including skis).
IDP isn’t worth the paper it’s written on. In fact it used to be paper with a picture glued onto it 😀 . Haven’t had one in over 10 years and been driving US and Canada okay on a British licence. In fact when I did have one they looked at it and laughed. They thought I was joking and had never seen one. They had to get their manager to approve it otherwise were going to refuse it. Now we have photo licences it’s really not required and a photo licence will work as ID for bars etc.
What you may need is a check code for your licence, which many of the major rental companies now use. Need to generate a code before the trip. Then they can check the licence online.
https://www.gov.uk/view-driving-licence