RichyRich,
How about booking a "lesson" and arranging that you do all the flying and the instructor, while offically P1, is really acting as a safety pilot? A comprehensive preflight brief to make clear what's going to happen during the flight is important*.
Obviously this is not going to guarantee a flight as the weather may be below the instructor's minima or outside of aircraft limits (e.g. icing) but will be more flexible that the minima you can, or wish to, use.
You may be able to perform bad weather circuits (a useful skill) or have the instructor help you fly through cloud to the nice sunny weather on top (definitely worth doing if conditions permit).
OK, it costs a bit more than flying solo but you may benefit from the extra contact time with the instructor and it'll help your currency.
MC.
* I think student-instructor interaction really should be studied in MCC courses if it isn't already
