Well tea, given the time.
I'm due to go at 5pm which I was looking forward to initially but as the day has gone on and the kids have been consistently playing up my mild headache has got progressively worse and my TMD is flaring up.
I'm stressed, overwhelmed and really can't muster the motivation to mess around getting two busses there and back (OH takes the car to work)
Downside is they will be very disappointed.
YABU - suck it up and go
YANBU - stay home