Reviews/testing information on UK car and booster seats?

Hey all. We're starting our search for the next car seat, the booster one with the high back(I gather stage 3/group2?). In the states I'd be using consumer reports to look at reviews of car seats. Is there a comparable site here?

I did find http://www.which.co.uk/baby-and-child/baby-transport/reviews/child-car-seats/. So, that'll help some, but as I'm not familiar with the site thought I'd check if anyone has any opinions. Or, for that matter, recs!

Thanks!

which.co.uk is a site run by the Consumers' Association, which trades as Which?, is registered in England and Wales and is a charity. The CA is well known for its unbiased and independent comparative reports and purchasing guides. They are particularly strong on areas like safety and value for money. They say theirs is "UK's only comparative crash test of child car seats".  I would say that Which? is a pretty near equivalent to the US Consumer Reports.

I was about to suggest Which when started reading!  They've been around a long time and are very reputable.