I can't post URLs yet but Google for What Car's car leasing site. Tick Private Leasing, and select Seat leon. Then put RF or Cupra in the filter box.

The best deals seem to be for the FR 150 petrol. When I was looking a couple of months ago, it was about an extra £40 a month for the 184 diesel and it just didn't seem worth the extra (unless you do a lot of motorway driving) as the petrol's nearly as quick. Petrol engines are a lot nicer to drive anyway, and with the petrol, I won't be giving my kids Asthma ;-)