The Thomson 767 fleet range from around 14-20 years old, so its unlikely that the older line numbers will go on another passenger lease. I see the two oldest L/Ns, G-DBLA (434) and G-PJLO (438), are being converted to a freighters.
They also have a handful at Arkefly. I'm sure the TUI Group could move some airplanes around to make sure they fulfill their obligations. Maybe Corsair could lend them a 747 or 330 short term to merge a few of the SFB trips? Can Thomson's own 757 reach SFB?
I'm sure Thomson have some flexibility built into their flying programme.