Complex sentence: For a while the band existed as a semi-pro outfit playing the college circuit, but it wasn't long before they acquired a manager, went full-time, and found themselves booked on the working men's club circuit mainly in the north of England.
Split into simpler sentences: For a while the band existed as a semi-pro outfit playing the college circuit. After acquiring a manager, they went full-time, and were booked on the working men's club circuit, mainly in the north of England.