Mine are now 21 and 19. The younger one has been twice.
The first time she was 4 or 5. She fell over at school and banged her head. I was at work, so my childminder collected her and took her to the minor injuries clinic who said she was fine but provided a sheet of things to watch out for. In the evening she vomited, so I took her in.
The second time she was 5 or 6, and we were in a car accident on the way back from school. Car was a write-off. My daughter complained of a sore neck so, to be on the safe side, the police called an ambulance and she went in on a stretcher and with a neck brace to get an x-ray.
The older one has been once, aged about 9. She slipped over on some ice and cut her chin badly (I could see the bone). It probably didn't need A&E but it happened on a Sunday and our local minor injuries clinic wasn't open.
I nearly took her in when, aged about 3, she bit the top off a thermometer and I was worried that she'd swallowed some of the mercury. I phoned for advice and they checked with the poisons unit at St Barts (I think) and concluded there was no need.
We've probably been lucky.