From the Ofcom FAQ for Mobiles on Aircraft...
- What has Ofcom announced?
Ofcom has confirmed that it will allow airlines to use the radio frequencies to enable them to offer onboard mobile services. However the Civil Aviation Authority and the European Aviation Safety Agency also need to approve these systems before they can be launched. It will be up to airlines to decide whether they will offer these services to passengers and when.
- Does this mean that I can now use my mobile phone on board an aircraft?
You cannot use these systems on board aircraft yet. Your airline will tell you if and when services will be available.