Where to buy in North London

Hi everyone, as per subject I'm looking for a endorsed, if any, dealership in North London. Do people have any experience with them? I tried an advanced search in this subforum but with no luck, only independent garages came up.

Also, important question, as you can notice I currently own a Corsa which is usually get serviced and looked after by a well known tuner and, as you might know they sell a tuned/road legal version of the VXR platform called VXR-R and VXR-RR. Is there any equivalent "product" out there at the well known delar/tuners?

Any info will be highly appreciated. Thanks.