I have a few jobs sounding like this.
Dunno how you clean but i had 4 very similar elisabethan houses with thick oak window frames. 3 came up lovely with wfp eventually, the other always needed detailing whichever method i used.
I also found microfibre much better for detailing than a scrim.
I reckon however you approach it, you should go back and check the 1st clean has dried properly if you are using wfp.
If you are trad then clean as any other window.
As for pricing it, compare the size of your £1 windows to the size of these wooden ones and up the charge accordingly.
If you can avoid cleaning the frames then do so. Pure water seems to pull all sorts of stuff from these old frames.