I remember some years back in the UK there were some mutterings about time limiting home made recordings (on VCR but I presume DVD would not be different) but it was basically laughed out of existence by the newspaper media.
Whilst there might be technically a UK law preventing recordings being held for over a certain period of time, I have never heard of it being enacted upon.
What is certainly illegal is to record a TV program and then distribute copies for non personal use (which in itself is open to interpretation - e.g. is lending a tape to a friend legal - the common view is that this is ok).
I don't really hold with the view re recording a TV series rather than buying it. I often buy a TV series simply as it is more convenient. It takes a lot of effort to record a program weekly, and remember to do all episodes.
In addition, TV series often cut action, and are of course often littered with adverts. People buy a TV series if it a) good quality, and b) reasonably priced.
Downloading TV programs from an unlicenced web site though is a different issue, as in some cases this is clearly piracy.