1) Ryanair - By far the cheapest if you don't care much about service or comfort.
Prices start at 8 Euros (yes, I've done this!) for a return flight
Routemap: https://www.ryanair.com/en/cheap-flight-destinations
2) EasyJet - Good bargains for advance bookings and operate a lot of routes
Prices start at 60 Euros for a return flight
Routemap: https://www.easyjet.com/asp/EN/routemap/
3) bmiBaby - Mainly fly between mainland Europe and the UK
Prices start at 80 Euros for a return flight
Routemap: http://www.bmibaby.com/bmibaby/where...route_map.aspx
4) KLM - Many European routes, and surprisingly cheap if booked in advance
Prices start at 100 Euros for a return flight
Timetable: https://www.klm.com/travel/gb_en/index.htm#tab=db_ott
Prices start at 8 Euros (yes, I've done this!) for a return flight
Routemap: https://www.ryanair.com/en/cheap-flight-destinations
2) EasyJet - Good bargains for advance bookings and operate a lot of routes
Prices start at 60 Euros for a return flight
Routemap: https://www.easyjet.com/asp/EN/routemap/
3) bmiBaby - Mainly fly between mainland Europe and the UK
Prices start at 80 Euros for a return flight
Routemap: http://www.bmibaby.com/bmibaby/where...route_map.aspx
4) KLM - Many European routes, and surprisingly cheap if booked in advance
Prices start at 100 Euros for a return flight
Timetable: https://www.klm.com/travel/gb_en/index.htm#tab=db_ott
Comment