Ds had grommets (for the third time) when he was 6yo, and that was the only time he was nervous.
I told him about a week before and asked him to make some decisions.
For example, the last time he could eat was 6am. Did he want to go to bed late after a huge meal, be woken at midnight for a midnight feast. Or go to bed early and be woken at 5am to eat.
Then we had the choice of what to eat.
In the end he wanted to be woken for a midnight feast of marmalade sandwiches, then go for a scoot round the estate afterwards and come back for a hot chocolate.
He also chose his pyjamas to wear and I took his comfort toy. I also showed him a present to open when he woke up.
At the hospital I told them he was nervous, and they asked the play therapist to talk to him.
We also had the Usborne book about going to hospital, which actually has a child with a sore ear, and there was a Mr Tumble about being in hospital.
Don't tell her she'll be better afterwards. Ds wakes up very slowly, usually is sick, and his ears hurt. If I'd told him he was going to make his ears better he would have been very indignant.
I also reminded him about waking up in a room with the nurses and not me, and about having a canular in his hand, both of which he found difficult on the first two occasions.