I think the most likely development will be a few dates over the very peak NI holidays, offered by Thomson Group / TUI, potentially originating from the mainland, or at a push a few VS departures again stopping en-route from Britain. I have heard no rumours regarding either though. I'm sure BFS management will be craving an operator to pick up this route though. Maybe in more economic sunny times.
Is there a reason why you have felt the need to book from GLA with Thomas Cook, rather than from BFS via EWR with Continental, or VS from LGW with FlyBE connecting flights?? Just curious. American Holidays package the VS option to allow financial security, flight transfers etc. Not sure if tour operators "package" using the CO option, but certainly is a popular option if booking each element seperately.