Ok, this is probably a very stupid question, so apologies, but..

The is no earthing in my bathroom, i.e. the radiator, hot and cold pipes to
bath, basin, toilet, also the plugs and overflows. The only thing that is
earthed is the 8.5kw shower.

Anyway looking on t'internet it appears that I need to cross bond all of the
above items with earth wire and then connect to the earth terminal in the
shower isolating pull cord switch.

Ok, here is the stupid question, currently (pardon the pun), there is no
danger of me getting an electric shock, as I never do, and never will take
any electrical item into the bathroom, and secondly the electric shower has
been connected correctly. So if I was to carry out the earthing work as per
regs, then wouldn't I be increasing the chances of an electric shock.

Basically I have a irrational fear that somehow the earth lead will someday
work its way out of the terminal in the bathroom isolater switch and then
make contact to the live terminal, and now suddenly all the earthed stuff is
live.

I want to get the bathroom upto spec, but I genuinely feel It'll make the
bathroom less safe.

See I told you it was a stupid question :-}

Jon