Most of the excursions from the East Lancashire mill towns would have been either day trips to the seaside - usually on Sundays, when the mills would have been closed - or one-way reliefs at the beginning and end of the appropriate town's 'Wakes Week'.
If you can get hold of a copy of "The Railways of Colne, Lancashire" by Stuart Taylor (Foxline Publishing, 1994. ISBN 1870119355), it will give you a huge amount of information about the operation of such excursions, as well as lots of photographs. Also by Stuart Taylor - in the same series - are "Journeys by Excursion Train from East Lancashire - Part 1: Colne, Nelson, Burnley, Accrington and Blackburn to Blackpool and Fleetwood via Poulton", which I believe includes the Great Harwood Loop and "Journeys by Excursion Train from East Lancashire - Part 2: Southport via the West Lancashire Line and Morecambe via Preston and Lancaster"....both of which are essential reading if you are interested in this subject. I have all three books but, after a couple of house moves, they're stuck in a box somewhere and I can't place my hands on them at the moment. They should be available from Amazon or on E-Bay though.