Since I landed at LHR yesterday, let me help.
This week they are using 27R for landers from 15.00 and 27L before 15.00.
From Monday, this will reverse and then change back the following Monday and so on.
If on easterlies they'll use 09R for take-offs and 09L for landings. These do not change. Occasionally 09R is used for landings but this is quite unusual nowadays and only affects the odd aircraft anyway.
The 27L and 27R pattern is quite rigid and there are set weeks for their usage pattern. What I'm saying is that even a full weeks use of easterlies using 09 would not influence which 27 runway was used for landings once the winds had turned back seven days later.
As for 23, well, used just once in a while when headwinds are strong for this runway. Actually used about ten days ago for a very short while. Certainly don't go and stand there waiting for an arrival!