JC,
From what I read before I did my PPL it seemed that "regular and often" was the concensus, say weekly.
Like you said, the lovely British weather can often give "no flying days".
It could be worth booking say two or three slots per week for learning, and banking on the idea that you may well only go up on one of those slots. On good weather weeks you'd then be going up more often.
I did a bit of learning here in the UK, and learned the rest on an intensive course for three weeks. Intensive courses can be good for some people, but you may find that you forget what is tought after quite a short time - it may only register in your short term memory. You may have encountered a similar experience when cramming for an exam (passing the exam with flying colours then forgetting the subject after a month or so!)
T.