Not aware of any UK gliding club that packs up for the winter (can't afford to). The plus side of flying at this time of year is that you don't get many people coming for trial lessons & student tend to disappear unless their hardy. The downside is that winter time is traditionally the time to do the annual servicings so you may find part of the two seater fleet are off line for a couple of months.
Agree with all though - start flying now & you should be well on your way to solo by the spring.
Blue skies