From putney bridge to hammersmith bridge

[pengles]

Agreed, he seems to know nothing, which makes me wonder what research he has done? Lines like " there are only 4 places to detect" .... is that the North Bank, the South Bank and ... errr...

Start off somewhere easy, like the South Bank near the OXO Tower. The foreshore is wide, there are several entry/exit points. Your working time on the foreshore is about 5 hours, the middle 3 being the most productive, the first and last hour restricting you to higher areas.

Here's one site with tide info / tables, for starters:
https://www.tide-forecast.com/locations ... des/latest

Any number of websites will give you weather info, including sunrise/sunset times, here's the BBC Central London page:
https://www.bbc.co.uk/weather/2643743
( actually, the 'tide-forecast' page gives sunrise/sunset times as well, but it's still good to know the weather forecast )
Now you can plan when you can make a visit that's worthwhile. Obviously, as we're in early spring, you're only going to get one session in a day. In summertime, you can get two visits in a day, sometimes, like 6am - 11am & 5pm - 10pm.

I ve been looking at the tide times and yes it is about going during a certain window of low tide. Theres roughly 5 hours before it reaches it tide peak again from its lowest point. At what hour do I get out there safely? Like the 4th hour?

Dalos, as long as the tide is going out you should be safe anyway. When it turns just make sure that you have a clear exit at all times to get back off of the foreshore. That's it really. Enjoy.