Quangoid,
Its funny how people who have never been to prison seem to know the most about them (holiday camps etc) based on what the media tell them. I'm an ex con so might have a bit more insight (you would think...)
Theres different categorys of prison (ABC & D) and within those prisons there are different regimes. Theres also a difference between state run prisons and private prisons. In essence every prison is different, but the fact remains that if you get sent to prison, you are going to be banged up with some pretty unsavoury characters.
Ive seen beatings in prison (con on con and screw on con), ive seen more vunerable prisoners get bullied, ive seen attempted suicides, ive seen really mentally ill people banged up that really should have been in hospital rather than jail.
In short, prisons may have some creature comforts like tv nowadays but they are still hell holes that the majority of people who see them as a Butlins would not want to go to.