Thanks everybody for your fast and in depth replies I really appreciate it.
I am liking the blue one that guix has posted a picture of as it looks tidy and has screw holes which is handy as it is going inside a wooden enclosure. However is there one similar available with just a single relay due to space saving?
Thanks!
Edit: This one should do the job right? (http://www.ebay.co.uk/itm/1-Channel-5V-Relay-Module-Board-for-Arduino-PIC-DSP-Optocouple-SRD-05VDC-SL-C-/160881308759?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item257545f457&_uhb=1)