Have you got contact details for the pre-op nurses? They probably know how lists in your hospital are put together and can explain that, even if that ends up being confirmation you're likely to be at the end of the list.
They / your GP might be able to prescribe anti anxiety medication for you to take on the day of the surgery. If you're especially anxious they might be able to let a friend/relative stay with you in the waiting area.
It's better for your recovery to only fast for the minimum time required - your body will be working hard after surgery to heal the bits the surgeons were working on and it needs fuel and a good supply of protein for that. So a late night snack is the choice I'd make - for better healing and for more comfortable waiting.
Guidance for children now talks about waking them to give them a snack before the fasting cut off times.
It's also better to not be dehydrated so again stick to the minimum time for not drinking. This will help them with finding a vein for a cannula and help you by not feeling too rubbish. Look up 'sip to send' - you'll probably be able to carry on drinking still water whilst you're waiting. Lip salve will probably be ok and there are dry mouth gels which are worth asking about.
There's usually internet access in hospitals so you can plan the day with activities to do whilst you wait - if it's too hard to concentrate on a book you might have some games to play or shorter things to read online. You might also find interesting spontaneous conversations with the other people in the waiting room.
And yes, a lot of the challenge in managing healthcare is in managing uncertainty - you can't control the list or your operation potentially being cancelled on the day. So control the stuff you can control. Have a snack of your choosing with you. Have a fun evening back up plan if surgery doesn't happen.
Do you know what you're scared about? Pain? Anaesthesia? Losing control? It's possibly worth poking at that a bit and talking to someone about it.
It may help you to remember that it's your choice to have this operation. Nobody will make you. You can ask about other treatments or decide it's not worth the risk of surgery.