Currently:
G-TUMA in MAN
G-TUMB in MAN
G-TUMC in MAN
G-TUMD in MAN
G-TUMF in TFS
G-TUMG in MAN
Not ideal having one stuck in TFS as passenegers will have to be rescued and no one can be sure how long it will be stuck there. I suspect TUI may have anticipated this, hence not sending a MAX to HRG as it would have been far from ideal being stuck there.
Fortunately, for now anyway, they have announced that all flights will operate as planned but on different aircraft rather than cancelling anything. I know it is never in TUI’s interests to cancel flights (being a holiday company) but will they have enough slack in the schedule to cover this? I suspect some days may be fine but others not so much (Saturday ski flights spring to mind). I would imagine this will involve a huge number of positioning flights and possible leasing/chartering of other aircraft. A fair few of their aircraft (737/767) are still on lease in Canada and Scandinavia as well as 787s frequently working from Scandinavia and 757 withdrawal plans.