You are correct in your assumption, in one of the photographs you can see what appears to be a balcony support - Balconies being a major feature in many Chapels built in this period. I would also expect there to be a school room attached to the back or side of the building. Education of the Chapel member's children was a major feature of the Movement and was not restricted to Religious studies - many Methodist children went on to do great things in their adult life only because of the education they received in these Chapel school rooms.
Sadly many have ended up like this example or demolished years ago. Rawdon where I live was the hotbed of the non - Conformist Movement at its start, old maps indicate seven Chapels within a two mile radius if my present cottage. The nearest was fifty yards up the road - now a house. Of the rest only one survives and is still a place of worship. Sadly all the others, which were an important part of the history of the Methodist movement were raised to the ground years ago. Burial grounds and the odd foundations in the woods being the only reminders - At the start, Chapels were built in out of the way places to avoid persecution/trouble.