Hi Mate, if you have a decent loft, all you will need really is some perches which you can buy very cheap, from
http://www.kingstownkennels.co.uk/pigacc/pigeon_accessories.htm
And as for the winter, as long as the loft is damp and weather proof, they should be OK. What I am going to do, is when I get my new loft built, I am going to buy a low wattage & cost, panel heater, and place that in the middle of the loft for the cold winter nights. But if you are going to do this!
for SAFETY REASONS! make sure you get it done by a profession electrican, or someone in that field!.