The 863 - 865 MHz licence-free frequencies will not change. They are legal all over Europe (all ETSI signatory countries) and this will remain so.
If the use is at a single site, you can get a fixed-site "co-ordinated" licence. Talk to JFMG (and Sennheiser UK) and you can get a licence for frequencies that can be used both now and after the switchover.
If you need mobile "shared" frequencies you have several options. Ch.69 is used now and this will change to Ch.38 after 2012. 3000 and 5000 series can be re-built to the new channel (talk to Sennheiser UK about costs). The government may finance this change, but have yet to make an official announcement on this. You *can* use Ch.38 in large parts of the UK now, and where you can't there are likely to be frequencies in Ch.39 or Ch.40 available - you would need to discuss this option with JFMG as I am not sure of the licence costs (eg: it may end up cheaper to buy a Ch.69 system and convert to Ch.38 later).