Agreed. I wouldn't even drive it to Trax if it's as bad as you say, it's really not worth the risk. What happens if it locks up on the motorway, chucks you into a spin and then you take out four or five other cars with kids in? I know, I know, it's a longshot but it's not impossible, and ignoring everything else that would happen afterwards (insurance, legal etc) you'd feel absolutely horrendous for the rest of your life.
It's only a car, it's only one day, take something else and just enjoy it rather than place yourself and others at risk.