My DS had this surgery at the same age. He was allowed to drink breastmilk until four hours before, and water until two hours. I made sure to offer him plenty of opportunities to feed/drink in the run up. I took several different types of dummy and although he didn't take to one long term, luckily he did take one on the day as he started getting a bit grissly before he went to surgery and they were running behind.
I stayed with him right up until he was unconscious on the bed from the gas and then said my teary goodbyes! I don't remember how long it took but I took myself off to the canteen to wait.
He was really upset when I went to pick him up and was too upset to take the breast even though he must have been starving. It felt like he was crying for ages but it was actually only an hour. Bouncing up and down vigorously soothed (or confused!) him but he still was too tired / upset for the breast so we took the instant aptimil bottle that was offered to us and he guzzled it and fell asleep. I pumped and stored it in the fridge in the ward kitchen. He then woke up normally to breastfeed a few hours later.
We brought a blanket from home that would have the smells he was used to. It was really hot in the children's ward so he lay on it rather than having it over him and he just slept in a vest (and this was n the middle of winter)
I was really frazzled and emotional after the whole day so my husband took over for a few hours.
We found that laying him with his head/shoulders and legs raised on pillows took the pressure off his groin. We made sure the nurses kept up with the pain relief (calpol and ibuprofen). We were released the next day and he was pretty much back to normal, happy self. We kept up the pain relief at home but he only needed it for a few days.
He's now two and it's all a distant memory. He has a very fine scar in his groin but it's getting less noticeable all the time. At the time it was very scary, but looking back it was all absolutely fine....even the bawling!