George,
It's still on, the weather forecast is decent too. No trains on the Bexleyheath line but I guess you'll be taking the Elizabeth line from Woolwich (as will I).
To all,
Recommend water, sun-hat and sun-screen, if current forecast holds (26C and sunny).
Found somewhere to eat lunch, Richard's pub,
Waterman's arms. there are a few other choices around Island gardens.
I'll leave it up to you if you bring a Tripod. Low tide is 14:05 and there is foreshore access along the walk.