You know, this thread has re-lit the fires.....
On my wall is a photo of me at Bus Stop on my first trackday with Ron at Mallory Park in 1997. I remember how I felt...nervous as hell on the drive up, even more nervous as hell at the briefing and the most possible nervous as hell as I threw my shaking leg over the bike.
I waved even more shakily to the pit lane marshal showing him my track access wrist band then dropped my visor down and followed the instructor and the other guy who had been teamed with me on our 2 to 1 session. I had been riding since 1972...Triumph T100C, Z900 and GSXR 1100 but still I felt totally out of my depth....for about 200 metres. Into the long Gerards bend (with about 5 apexes) down the back, little kink at Coopers, then Shaws, Bus Stop, Devils and then..wow open her up for the straight. Before I knew it I was there, head down under the screen blatting down the straight. That was it, it only took 5minutes and I WAS a racing GOD.
Then the instructor signalled me and my companion (assistant racing God) into the pits. I can't remember his name now but he was a BSB (or equivalent) rider. Having edited out most of his quite prolific and adventurous profanities, the gist was:
"You two know f*** all about riding motorbikes!"
"Any **** can ride fast on the fast bits like you f*****s are trying to do. What you p***ks have got to learn is how to ride fast on the slow bits......W*****s!"
"Now go out on your own and practice and DON't fall off...t*****s!"
Having digested this constructive advice went carefully returned to the track for about twenty more laps. Learning braking points, apexes, power on/off points slowly, the lap times started to get better and then...my knee touched the track! The rhythm just started, lap after lap..I was even getting rear wheel skitter coming into the hairpin.
As others will tell you, just a great experience and one that takes days to come down from. I don't know how many I have done now but I do know it's time for another....
Do it, you'll never regret it.....unless you fall off and break your leg or something

...which you won't because, as a beginner, even when you are trying very hard the bike will still have a long way to go.
Hope you go to one and enjoy.