Hello Robert,
No problem coming along to spectate and watch.
To take part you would have needed to have signed the paperwork and had your LR scrutineered, which is a basic safety check, at the start of the day. (If the basic mechanicals make the vehicle roadworthy and suitable for an MOT I wouldn't expect a problem with the scrutineering😃) Unfortunately, therefore, it would not be possible to enter part way through the day.
A TYRO is not demanding on the driver or vehicle and I would encourage anyone to give it a go. Most people find it is the best £15 worth of entertainment they can spend!!! If at any point you feel uncomfortable you can sit out or if you would like some advice, plenty of people will be more than willing to give it. Also if at any point you would like an experienced TYRO competitor as a passenger there will be plenty of volunteers.
Hope to see you there,
Dean