I think your going to struggle for 5/6 flights for £200 each, the best I could find with a quick look was from Manchester with flythomascook and they were awful flight times for £244 pp. Even slightly altering your dates to go on the 2nd for 2 weeks only marginally changes the prices to £223 with Airflights.co.uk Good Luck

got flights from manchester through airflights.co.uk from 2nd september returning 16th september for 2 adults 3 children 1 infant for 1110.00 inc taxes etc,we have a turkish friend picking us up at dalaman so total for flights and apartments is 1350.00

roll on september