Complex sentence: Their first performances were in local pubs in and around Southend as a part of the area's well-known R&B scene which had begun in the 1960s; they initially formed "to have a laugh" and didn't take themselves too seriously.
Split into simpler sentences: Their first performances were in local pubs in and around Southend as a part of the area's well-known R&B scene which had begun in the 1960s. They initially formed "to have a laugh" and didn't take themselves too seriously.