I disagree. Winter can have cr@p weather - but it can also have clear frosty windless days that are perfect for flying. Spring can be OK - but likely as not it'll be windy or foggy or raining. Summer ought to be good - but half the time you get high pressure and cr@p visibility. Autumn - back to high winds and rain. In fact, in the UK the only thing you can be sure of is that whenever you start, a large proportion of your lessons are likely to be cancelled, and you'll learn more about patience than flying. Which, if you intend to fly in the UK, is not such a bad thing - because guess what you'll be doing when you get your licence. So go for it and start now; you might be lucky with the weather. You might not, but that applies equally to any other time of year.