Flights JQ747/JQ748 are to/from Launceston Airport, which does not have aerobridges:
Due to airport operating restrictions, Launceston airport cannot provide aerobridges to board aircraft. All access onto the aircraft is via aircraft stairs or mechanical lifting equipment (Disabled Person Lift) operated by the airlines. airline staff
will provide the assistance required to board the aircraft in an appropriate manner.
I would strongly advise you to contact the airline and notify them that you will likely need assistance, and arrive early for check in so you can ensure they're ready.
On the Sydney side, Jetstar flights typically do use aerobridges, but these are some bus-only gates as well. The airline will be able to advise you regarding this as well.
As for a generic way to find out, I suppose you could always look at the airport in the satellite view on Google Maps, but even if the airport has gates does not guarantee that your flight will use them. So, again, contacting the airline is by far your best bet.