If you’re paddling on the non tidal section of the river (Cricklade Bridge to Teddington) yes, you need either a non powered pleasure craft licence available from the environment agency here or join Paddle UK here. Either of these entitles you to paddle on the non tidal section of the Thames.
If you’re paddling on the Thames below Teddington you do not need a licence, just remember the Thames here is tidal and a look at a tide table before you go out for the day is very sensible Met Office Timetable some more information regarding paddling on the sea can be found here on the Go Paddling web site
Other local river such as the Wey or Mole and the Basingstoke Canal and Wey Navigation are also covered by the Paddle UK licence.
If you have any worries regarding river access locally either have a look at British Canoeing's Go Paddling site by clicking here or give us a call on our normal number 01932 247978 as we can normally help!