If you're a member, talk to AOPA and get their advice.
Tudor Owen, a renouned aviation barrister gave a talk on Sunday at the Fly show at which he strongly advised that you make notes on what happened ASAP and talk to potential witnesses ASAP (i.e. the ATCO).
If the CAA do approach you, don't say anything until you've asked them what they intend to do with any information you give. If they intend to prosecute, they should tell you but don't always do so.
Mark