Hi ****egun
great to hear you're back into track
.
I'm not going to comment on what training you can do on your own - that is hashed over in all sorts of threads, and a lot of folk can give you better advice anyway. But basically, at first, any training is good training. my personal recommendation is to do a lot of reading (stickies on this forum, articles online, magazines etc), and create your own plan. Make it reasonable, and stick to it.
All cycling computers i've come across give you time
and distance. Many don't record in tight enough increments for track, but a few will record at second intervals, so go for one of those (i believe garmins do, and i'm sure there will be others - do some googling). There will be a little lag if you're going on speed and not power, but it gives a good indication until you fork out for a power meter. You can get an idea of what is going on, and since you'll be looking at the same data parameters over time, its comparable, and thus gives you a measure of progress.
if you want 'harder' data - find a buddy to go through to the track with you when you want to get a milestone. they can time your efforts like any coach would do. times week to week are noisy data - the trends (over a longer time period) are more useful. (Equally, trends over your 'milestone' data. everyone has bad days).
Happy riding