✔ 最佳答案
Well... For low cost airlines, they always add up your fare per way anyway... So I am thinking if you would consider flying London-Paderborn-Milan-Venice-London as your flying pattern... This way, it should save some cost of having to buy a return ticket... You can also look at EasyJet (
www.easyjet.com) or Ryanair (
www.ryanair.com) which do fly from Venice-London... And of course, as you have said, Air Berlin on London-Paderborn-Milan... If you do this flight pattern, it would be EUR24+EUR50+EUR75 basing on oneway and the Vence-London section could be cheaper if you fly with EasyJet or Ryanair rather than SWISS...
Buying a 1 way ticket is usually expensive unless you are flying with Low Cost Airlines like Ryanair/Air Berlin/EasyJet which count fare per way... So I would suggest you to book Hong Kong-London return with Oasis Hong Kong...
And to be honest, if you are planning to visit Kassel+Venice+London, and you will need to fly from Paderborn-Milan, you can have a bit of time in Milan as well... But this should be a rush for 15Days already... So I would not suggest anymore place to visit... London+Kassel+Venice+Milan should be more than enough...
Hope these will actually help you...