Absolutely nonsensical, though I suspect that this is another example of the Anglican Church throwing its weight around in the political sphere again; if I recall correctly, they tried something similar in the early 1990's with imports of the Hustler magazine.
I'm sure their nonexistent weight was very influential in this legislation. 
Are you joking? Most of the Christian Democratic wing of Labour are more beholden to the Church than to Labour proper.
The Church has no power at all in Britain (or indeed, anywhere in Western Europe), and hasn't had any for a long time.
Necrophilia and bestiality are banned. I don't see anything objectionable about this.
