We have PHI and DS2 has had grommets twice, the second time was also adenoids removed. I hardly paid anthing at all, just a gap cost for the anaesthetist. I would suggest straight to an ENT. If you have PHI and the ENT sees that he needs grommets, this could all be fixed within days of seeing the ENT. If it's the same ENT you should get in quickly as existing patients usually have priority of appointments of new patients.
The ENT also has a special little tool that he grabbed quite a bit of wax out before he could see DS2's ear drum and discovered glue ear. It was like a hook at the end and it was quite surprising to see how much wax came out after he dislodged it using this tool with which DS2 had no idea what was going on.