Looking for a Hard Case/Shell for my new Retina MacBook Pro 15"?

I am looking to buy a shell/case for my rMBP (October 2013) it hasn't arrived yet, but obviously I want it to be protected asap.

I don't know what the model number is, but it is the lower spec 15" Retina MacBook Pro that I have purchased. How can I make sure that a case I buy will fit?

Will any 15" rMBP case fit, or has the size changed for this upgrade?

I am looking for either a black/clear, shell/case that will attach to the back of the lid to protect it. I am looking on eBay at the moment, as I have a voucher to spend on there anyway. Can someone recommend a shop/seller or a particular product?

I am in the UK, so I would obviously prefer to buy from a local seller.

Thanks!