I have some LV halogen lamps I want to put in my airing cupboard, but they
are supplied with a plug-in type transformer. The most convenient supply is
a lighting radial, but I can't fit a socket of any sort to a lighting
circuit, am I right in saying? Is there any way I can supply a plug-in
transformer from a lighting circuit?

Next option, more difficult, is to supply it from the mains. I have
nearby a radial from the consumer unit which runs the immersion heater: also
split off this radial ( at an unknown point, probably under the
floorboards ) are a 300W shower and the central heating supply ( pump, timer
etc ).

Am I allowed to add another spur from this radial to a 13A socket,
which I can plug the 2 x 20W lights into, via their transformer? Also,
whilst this is technically a fixed electric appliance, I can't see how I can
work a fused connection unit ( say 3A ) into things, as the transformer must
plug directy into a socket. My thoughts are that I don't need a fused socket
or whatever, because these things are intended to be plugged into whatever
13A socket is handy.

Any advice appreciated,

Andy.