It’s well easy, you get used to it so quickly, and the less experienced you are at driving in the UK the better, I would say (to an extent). When you pick the rental car just take it to a spin on quiet roads or around a car park to get used to things.
Also not sure why people are worried about going the wrong way around roundabouts - isn’t this virtually impossible as you are angled into th curve of them? (Usually idk).