Just to add, my friend used to work for 2 Airlines at Manchester Airport so he knows what things can be like. He arrived at the airport two and a half hours before his flight.
He joined the Jet2 check-in queue which stretched out of the doors as far as Olympic House. He checked in, dropped his baggage and collected his boarding pass.
He Immediately went to security and it took him 45 minutes to go through nobody was calling passengers forward. He still thought he had plenty of time.
On entering the main departure lounge he noticed that the Barcelona flight was departing from Gate 28 which is at the end of the pier. He ran to the gate but missed it by 2 minutes. The Air bridge had been removed and they were searching for his baggage.