luxury car rental in uk?

[miamikid2]

im going up to dundee in scotland from wiltshire in the south so i want to rent a luxury car, what are cheap reliable rental places in uk? id take a merc m class or equivalent, or a merc e class or equivalent, or merc gl or s class but obviously they will be more expensive. im looking to spend as little as possible but i have seen them at £145 per day (i want it for 2 days) and as little deposit as possible and do they come with insurance or do i have to get that? i know how if i have to. thank you in advance