I did it in 2015 in one go, following the excellent Trailbazer guide, from source to the Thames barrier. I did a mixture of camping and b&b - around the middle of the walk, a few of the locks have campsites, which were great. Happy to answer specific questions.

We did not use a guide book - we used the OS 1:50k map. The route is well signposted. You can choose your direction. They always say walk West to East to have the wind and rain behind you, but that often does not work!
We did the walk in bits and did not finish at either end.
The main thing is to do the walk because it is completely amazing.
We started on it during the foot and mouth as London was the only place you could go walking.

Hi , we are planning to walk the Thames national trail in sections this year. We live near the source and were thinking of starting this end. I was considering buying the Cicerone guide book but this does the trail from Thames barrier back to the source which set me thinking about which way would be most enjoyable. Any experiences/opinions/suggestions welcome. Also, if you walked from source to estuary did you use a guide book that you can recommend. Many thanks Liz