Just looked at the UK site of TUI Holidays
and their Flights pages (plus looked at the UK TUI ''Our fleet'' pages)
and any reference to the fact they have the 737 MAX has been quietly airbrushed away from everything.
Even a FAQ search for Boeing 737 Max brings up zilch...
At this time of year their winter flying program (Nov-Apr W19-20) will be settled, and I gather they are not including any of the Max fleet in this schedule (they have 6 Max on the ground and 3 at Boeing awaiting delivery since last May)
The winter program should be well covered by their own 738NG and 757 fleets without any, or much ACMI needed if the Max does not return during the winter - The BY 757's use
AFAIK have been extended - but into next summer 2020?
However next summer's program S20 is a different matter to now re-plan and cover - Decisions have to be made now on the capacity needed - If the Max is not back to certify (and maybe likely re-branded) by the end of this year then TUI UK will either have to sort a lot of ACMI again, as seen this season costing £millions. Or, reduce their program of holidays they sell.
The cost to TUI UK just to the end of this season for the ongoing Max debacle has been estimated to be £600m. Ouch.