If you want to take this opportunity to visit North and South America during one trip please look for travel dates till 26th of June 2015. Max stay 30 days. Valid for bookings made till 25th of February 2015 or until sold out. Do not forget to issue US tourist visa or ESTA certificate prior your flight to/via America. Another alternative with American Airlines are open-jaw flights to remote Bolivia available already for Ł436 (€580).
Booking samples
Barcelona - Lima for €501
Barcelona - Lima - UK from Ł375
Barcelona - Cuzco - UK from Ł439
Barcelona - Peru - Germany from €519
Barcelona - Miami - Lima - London for Ł390
Barcelona - Miami - Lima - Germany from €543
All these European cities are well connected by many low cost airlines. To make a basic idea how to reach them from your hometown you may use service of Skyscanner. If you want to book your accommodation in advance you may compare hotel rooms offered by most of leading booking sites using our tool here.
Booking sample of an open-jaw flights to Peru Ł375 here. In this case you would be flying from Barcelona to Lima on 2nd of March. Your return flight from South America to Manchester would take place on 24th of March 2015.