running it from the plumbing the best idea, or running it from
electric? very often i think i would want just the towel radiator on
and no others

I recently did my bathroom, and turned a normal towel rad into an
electric towel rad - you can buy straight elements (even B&Q do them)
and adaptor elbows, which allow you to use both systems - the water is
pumped as normal when the CH is on, but heated electrically when you
want it.

ISTR I paid slightly over the odds (about £27?), but was impressed
with the service nonetheless - and the adaptor elbows were a couple of
quid more - mine was from http://www.carltontech.co.uk