Welcome onboard

I'm mobile at the moment so I'll give a more detailed answer when I'm home. Your flights, BHX-CUN-BHX (TOM568/9) are indeed operated by an ex-TOM 76W. G-OBYD is the long haul ex-TOM aircraft so should be operating your flight. The aircraft operates BHX-SFB-BHX (TOM630/1) the day before. Fuel stops, if reqired add an hour to the flight. It's due to BHX's runway not being long enough to allow the aircraft to take-off with the required fuel to make it all the way to CUN, so it used to stop in MAN to brim the tanks. However, the additional performance gained by the addition of blended winglets has offset this so now operates non-stop. You'll find extensive aircraft information on our What Aircraft? guide (link below).
EDIT: additional information added.
Darren