Giles - a university is able to decide for itself what modules and topics it wants to teach and at what level, based, I assume, on the interest and aptitude of its professors and lecturers. Different universities also have different entry requirements so those that require As and A*s at A Level will go into topics in greater depth and tackle more complex things than one that requires Ds to get in.
A degree in Biology from, for example, Imperial College London, will be worth far far more than one from, for example, De Montfort.
Although there are some universities which have a low ranking that are particularly good in one particular subject - for example, Portsmouth - a low to mid ranking ex Poly - has, I believe, a good reputation for Marine Biology.
I thought the programme was pretty well balanced. Warminster isn't an especially good private school, I don't think. And Bemrose didn't appear to be an especially bad state school. I think ITV did well to avoid sensationalism or the showing of extremes.
I really hope Brett gets a chance to try Warminster.