Car rental for UK young driver?

Hello, i am going to Pisa in 2 weeks and i would like to get a car rental that would accept UK licence and the fact that im young (21).

I have been to Brazil earlier this year and rented a VW Tera (small crossover) for 4 days and it was like less than £150? So that was a pretty good price. I just searched up whatever appeared first on google and got about £600 for 7 days in Pisa on an automatic crossover.

So what are the best websites/places to rent a car? Main reason why i want to rent a car is to drive to the Alfa Romeo Museum in Arese which is around 3 and half hour drive.

Thanks!