Complex sentence: Sid is outside with Cassie who is on the trampoline, whilst inside the house Chris, Tony and Anwar get into a fight with the posh lads and one of a Polish girl takes a fancy to Chris.
Split into simpler sentences: Sid is outside with Cassie who is on the trampoline. Meanwhile inside the house, Chris, Tony and Anwar get into a fight with the posh lads and a Polish girl takes a fancy to Chris.