In the same way as it is assumed Ryanair might not wish to enter LGW in a large way due to the size of EasyJet's operation, I wonder if Jet2 would really opt to move on LGW where they would compete head on with Tui.
They had the opportunity to do so when TCX collapsed and didn't do so, instead choosing to offer some of those routes at STN.
Whilst there may be more free slots when this resolves itself and I am sure there could be some deals to be done, I would suspect they are likely to see better results growing their existing market rather than taking on an already successful incumbent in what could be a very different market,