" I'm on waiting list for ENT. "
Do you mean that you are on the list for consultation OR you have been seen and you are on the list for an operation or procedure?
If you can't swallow the Omeprazole, there is little point in taking them as their action will be lost. I suspect that you were taking them for "acid reflux (GERD)" and in which case i would stop the tablets and buy a liquid antacid e.g Maalox as a temporary measure and see how it goes.
If this controls your "acid burning" then fine, keep on with the change of tactics, but if it doesn't and you still get reflux, then see your GP to expedite your E.N.T appointment.