Some good tips above - I also have some pretty badd tinitus, up to 45% in some frequencies!
So far I have found that you are usually better off than you think. Tinitus usually affects only higher frequency hearing and most of what we need for the radio is beneath this. In fact I was recently told that even with substantial losses at the top end of the frequency band, I have lost less than 5% of my hearing overall.
The other news that might be good to hear (read??) is based on a coversation I had recently with a long serving pilot who had significant hearing problems for many years (he now wears an aid and is no longer on the line). He told me that even when his hearing was getting quite bad on the audiogram, he was given opportunity by CASA to demonstrate that he could understand radio traffic through a headset in order to maintain his medical.
Not quite definitive info, but hopefully a good indication of where you stand?