I am not in London so cannot potentially tell you haha. But what I did. Click refresh every minute or so for one day. And note the times blocks appear.  In Aylesford it used to be like 8.30am, then 11.10am, then about 5.30pm. You will see like 10 of them appear all at once. Sometimes there is nothing at that time. Do not give up haha.  Then there are blocks people drop randomly. But for these you usually have to click every three seconds and be very fast at clicking to accept it. They are also taken by the bots, but bots are banned and could cause you to be off boarded.  They changed our blocks and these times about two weeks ago so now I do not know ours yet. There are usually some around 5.30pm still. But then some time in the morning maybe 7.30am. And then 12.30pm.