I've ridden the Thames path at various stages between Putney and Windsor.
There are a couple of places along the path that can end up under water as the tide comes in between Barnes and Kew.
At Weybridge you have to cross the river to keep going along the path. You can either do this by taking the ferry across which is run by the boat shop on the opposite side or by taking the road bridge at Walton and riding along the roads to pick the path up again.
And the other thing is the path swaps back over to the other bank at staines, so you will have to cross the road bridge there.