We're trying to get from Cracow to London in order to fly home on Virgin this summer. AFAICT all the intra-europe flights share the same luggage policy--20-25kg max luggage weight per passenger, with a overweight charge of 5-12 euros per kilo and no option for a second bag. We'd like to bring an extra suitcase of personal effects.
Lacking any other reasonable options, I had the bright idea of going EasyJet to London and just buying an extra $122 ticket so we could bring one more suitcase. But I'm not sure if that's even possible, and not sure if EasyJet is still going to hold me to the 20 kilos per person.
What we ended up doing was flying first from Cracow to Frankfurt on Lufthansa, and then buying a completely separate ticket from Frankfurt to London (not even on the same itinerary). Cracow isn't big enough to have a lot of international options, and going to London leaves the Schengen zone. Trying to get directly from Cracow to London had too few choices. And Lufthansa has a reasonable baggage policy.