Some 10 day forecasts show weather getting drier in southwest UK with the end of July being sunny. But 10 day forecasts can be inaccurate unless the weather is quite static.
Discussions of Jet stream influence - see for example
link from BBC science
and for more detail on Jet Stream generally:
all about the theory of jet streams
Summary sent to me today:
The Jet Stream has fixed itself in an unusual position; it usually moves around more, and north of the UK. It is currently in a more southerly position around the globe - and frighteningly fixed, without any known scientific reason. This explains the constant rain here - and the extraordinary heat in the US.