From my own experience, I'd say that OU courses are excellent, and well worth the money you pay. Most of the courses are subsidised by the government anyway, so it's not as expensive as you might think. I've had other people who say they have done both University and OU courses say that in many cases their OU course was better, but of course that's a matter of taste, some people prefer more guidance than others. An OU degree still takes as long as university degree part time, but you can stop and start at certain levels.
You may start for example as I did with a certificate in science(or arts or whatever your looking to study if you don't have A' levels). which enables you to take any science course bar physics without further study. I am currently doing the second part of what would roughly be equivalent to a maths A'level, in order to then start a 6 year or so part time degree in Physics. I can say at least from my experience the OU has been very educational and highly rewarding for me.I am someone who missed out on a University education in earlier life because of health reasons.
Alex I work in Soton myself. What degree are you doing as a matter of interest?