Barry, if you buy in the UK, 40K GBP should get you a lot of car for your money. Everything you have suggested is a good buy, but I think the Germans will have the edge over the Aston for reliability.
Some other cars for consideration:
BMW 635 Twin Turbo Diesel - a mate of mine has one of these, it goes like a rocket and averages 35 MPG. If you don't like diesel go for the 650, it's nearly as quick as the M6, but a lot cheaper.
Audi RS4 saloon or avant, or RS6 saloon or avant (old shape)
MB - CLS AMG
MB - CL500 or CL63 AMG
MB - SL any model
Jag XK8 - new shape, beautiful car and more reliable than an Aston
Aston DB9 - 6.0 V12, and beautiful
Good luck with whatever you decide to go for, take the opportunity to test drive everything, and keep us all updated