I attended an Essex Canoeing Association meeting last night.
One of the attendees was distributing information about an event on the 20th January next year to raise funds for the RNLI. It's a 4km paddle for kayaks (other boats!).
Apparently there will be all kinds of craft there on the day from gigs to SUPs so it would be good to get a few kayaks or canoes out there too. You can sort out any sponsorship on the day of the event.