I have known a few people who waited months for their QXC. 6 months in one case; the instructor would not let him go anytime on the hazy summer days.
An appalling indictment of the training system, that pilots cannot fly in less than great visibility...
This time of year, training tends to get interrupted by heavy frontal weather. I managed to get just 3 lessons in during oct nov dec 2000, and I was booking a lesson every day!
However, right now, Thursday & Friday, the weather in southern UK is fantastic. CAVOK, and nothing at
altitude either. Fantastic for long trips into Europe, VFR or IFR. Hardly a cloud over the Alps. I'd cram in a few lessons.