Low voltage halogen spots?

This is for UK electricians.

Want to fit Low voltage spots x 3 can't access loft Gable roof no trap door, only in main part of roof and the way rooves join, timber framing prevents access and I don't want to cut new trap door and roof is truss type so you have to watch what you cut out.


Is there a problem with running the 3 spots for occasional use over bed by way of extension lead fused at 5amps to feed the junction box and in turn to feed the transformer all boxed for safety allowing for air circulation re-heat. Its the guest room for visitors and when not is use lighting can be un-plugged from socket.
Was trying to get third wire in socket for a double pole 6amp switch to run lights from that be couldnt get the third cable in the terminals as spur.
OR am I an idiot to suggest this?.
Many thanks in anticipation.