At first everything seemed cluttered around the screen, but once you adjust it's actually a very fun game! The art is polished and fits well with the aesthetic and the theme, with the occasional cars being a nice touch.
Having greyed out unlockables is an amazing idea, it really gives the player a goal which is difficult in this kind of game.
The gameplay works well and has good pacing, all I'd say is that clicking the sell button yourself eventually becomes pointless since the game plays itself faster than you could ever click, so maybe a powerup that makes you sell more with each click would be useful.
Exceedingly British, as it should be. Nice work!