In terms of when to cruise, we only ever cruise during school holidays. No need to avoid them. The canal towpaths are not lined with raggamuffins intent on making off with your brightwork, nor are the canals filled with families cruising. The canals are pretty empty in the holidays perhaps because all the childless boaters give them a miss, maybe austerity has hit, who knows. I've only found two queues in the last 5 years of boating. (each delayed by about 30mins) in the summer holidays and not had a problem mooring. School holiday boating is not a problem.