Bike rack for a hire car

I’m going on holiday in the UK with family later in the year, and because we don’t own a car we’ll be hiring one for the week. I’d like to take my road bike with me, but there’s unlikely to be space inside the car (unless we hire something really big, which seriously ramps up the cost), so I’m looking at other options. Does anyone know of a UK car hire firm that will rent out cars equipped with bike racks or a roof rack? I don’t think getting a rack that mounts on the back is an option, as you never know until you turn up to collect it what sort of car you’re getting, so impossible to know whether a particular rack will fit, or require an additional numberplate and lights.

I’ve seen a couple of adverts for these recently: https://www.seasucker.com/product-category/bike-racks/ Has anyone got any experience of using them? They look ideal, and from reports I’ve read they do work and you can trust them, but I think I’d worry….