Tesla is just some car. Yes they are quick, yes they are electric....but they are not a sports car or special.
You won't get a good R8 V10 with the good spec/gearbox and low miles for your budget, so you are wise to park that idea. I think a 911 or Cayman is a good place to be and will work really well around London too as they are common and suited to city life too, a great all round sports car for a good reason. Cayman GTS is a great car and you should go and drive one, but if you can find a really nice end of line 997 GTS of early 991 I think that would be my comfortable place based on your budget. Others can comment on the V8 Vantage with a more informed view than me, but I would not take one over a 911 if I wanted to enjoy the driving aspect as a priority, 911 is the better drive, Cayman GTS perhaps even better.
Too add I can see the appeal of the Renault, but not convinced I would buy one over a Cayman.