Our own carmakers continue to turn out crap here in the U.S., but Vauxhall has some great stuff on the other side of the pond. This site I found about Perrys is one of the leading Vauxhall dealers in Great Britain. They have a wide selection of the Vauxhall insignia and the Vauxhall corsa.
I like this site because it has all the information you are looking for when purchasing a new car. It allows you to search both new and used inventory in the city of your choice. It is very comprehensive and easy to use. It evens lets you e-mail dealers directly with any questions you might have. Again, I am not sure how much of an audience I would have for this, but it is handy if you find yourself in London absolutely needing a car. Think of them as the Bob Rohrman of Vauxhall dealerships in Britain.