"My understanding was that almost all the UK radars were not yet configured to display any mode s info?"
Many of the UK En Route radars are already Mode S enabled, with a replacement programme to replace those that are not over the next few years.
However, in terms of which ATC units can actully display Mode S data to the controller, only the London Terminal Control Centre (LTCC) has the capability right now. Again, a programme to bring it in to London Area Control Centre and the Prestwick Centre (which is due to open in 2010 and subsumes Manchester & Scottish Area Control Centres) is planned. These are all En Route or Terminal Control Centres.
For airfield approach services not served by LTCC, the provision of Mode S to the controllers will be a local policy decision and will either require the procurement of a Mode S capable radar system and radar displays by the airport ATC provider, or for them to procure Mode S capable radar displays and buy in the data feed from a provider who has Mode S radar.
£££££££££££££ whichever route you take !!!!