Here is a list of useful links to model related websites

Rapidelectronics               http://www.rapidonline.com
 
Everything you could possibly need for model electronics

New Railway Modellers       http://www.newrailwaymodellers.co.uk/

An even better website than this for model advice

Gaugemaster                     http://www.gaugemaster.co.uk/

Everything you could possibly need to build a model railway