I'm [shocked] but not supprised, we had a terrible experience with ds1 getting to see the consultant (audiology fancy themselves as gate keepers here and its up to them when you have waited long enough - for us that was the whole of reception) once we saw the consultant its been very straight forward. For ds2 we bypassed the clinc and went private twice (2 sets of grommets so far) and private for the initial consultation for ds3 (too little for op at private hospital under 3's need specalist paeds team). Once on the NHS lists it has taken 6 weeks to get the op done.
We were very lucky to be covered by dh's healthcare, BUPA. We went to the Nuffield
First Consultation £120.00
Follow up Consultations £60.00 each time
Hearing test £25.00 or £50.00 (they give a hearing test at each consultation cost varied although I'm not sure why)
I'm afraid I have no idea how much the actual procedure cost, it was day surgery. The bill for the anaesthetist was £195 if that helps.
I also paid to get full copies of audiology charts and doctors notes, letters and reports. It cost £20 from hospital but has been worth it to have the data to back up my claims (for me that was to get School to recognise his difficulty).
Are you getting the support at School? IEP and strategies in place? this was a battle for us too, although from you NN you may know the system better than me 
I think any evidence from School, SALT, Health visitor - letters or phone calls they'll make on your behalf add weight to your request for grommets and may help with NHS system - it may be worth a try, sorry to suggest this if you already have.
In the meantime do you have any idea what ds's hearing level is? Would it be worth considering hearing aids to support him during this horrible waiting period? ds1 may have permenant high frequency hearing loss - he's now going into year2 and we are considering hearing aids to combate the flutating nature of his hearing.
Finally the National deaf childrens society have been a fantastic support, they really recognise the affect glue ear has on development and education, there is a discussion board too.
ps I'm sure DeWe wasn't being rude - she's been through the process with her ds and grommets and has lots of experience, I'm sure she just wants to help, she's given me great advice in the past x
Good luck with everything, I can throughly empathise with how hard this can be and hope you get a resolution soon xx