There seems to be lots of rumours flying around about what Tui's current summer plans are, I have it from Tui BHX crew that they will just be a 738/max & 787 base from May so no 757s with 787's operating flights if possible with Covid restrictions to DLM,PFO,AYT and BVC
The other one that I have heard from a few sources is that Tui will getting two extra brand new Max's that were built for a failed Asian airline this is instead of of Ex Fly Dubai aircraft. Personally I would be surprised if this is true as mid age 738 must be cheaper to lease than a brand new Max unless the leasing company just want to get some return on it quickly