Your insurance company can add the theft to StolenBoats.org.uk which will ensure that the details get circulated to the Police forces around the UK and other interested parties.
Do you have a better description or a photograph that you can post here? That might help too.
It's an old grey Avon Rover R260 with several patches, airdeck, yellow plastic seat, wooden oars, solid transom with "T/T Willow" marked on it. Unfortunately I don't have a photo.