With Thomas Cook increasing its long haul fleet both in the UK and with Condor in Germany, I'm guessing they will be thinking about fleet renewal at some point. Would they be more likely to order the A350, A330NEO or the 787's to replace the existing A330s (TCX/VKG) and 767 (DE).
My guess would be that a long haul order from the Thomas Cook Group is up for grabs for whichever lessor/manufacturer offers the best deal. I think the A350 will be too much airplane for what they need making it a straight shootout between the A330NEO and B788.