It sucks that you can't put the track time in, my tracks rather the opposite, never in use (opens 3 nights, 4 in the summer but that's for track league), and when it's not in use it isn't open to the public! Only usable when the club coaches etc. are there. Pretty damn sucky if you ask me.
No *free* ones until new years, is there any sooner ones that are maybe cheap? Also, are these sessions for absolute beginners? If you've got track time/confidence already, why not tag along to some other sessions (Adult beginners/intermediate) if they have them. I nearly said about another track, but your post says the Hoy velodrome, and I know how scarce tracks are in the UK.