Anyone who hasn't done this before ought to be aware of a couple of things;
If you're expecting to have a day blasting up & down the Thames, forget it, there's a VERY strict 12kn speed limit now for the whole length of the river where the race occurs.
You'll spend a lot of time hanging around waiting, if it's peeing down, it's not much fun.
The competitors can be an awkward bunch, my missus likened last year to "herding cats"
If you're camping, you will be on the water before dawn, so you need to be confident navigating in the dark & have lights. The race ends back at the campsite, so you will have done the river both ways by the end of the day, around 40 miles, it's a loooong day.
We were passing Parliament just after dawn & the city was silent & we had the river to ourselves, magic
It's one of the best days out you can have with your clothes on
We loved it last year & have no hesitation doing it again.