CLs in winter.

Hi

We are planning a Scottish trip late December through into the New Year. Is there any way short of wading through all the sites in the book to find which CLs stay open thrroughout the winter? I notice there is a list of Club Sites, but nothing for CLs. Being new to this, can I ask if it necessary to book a long time ahead at this time of year? We are more used to the continent where just turning up is usually not a problem.

Regards