Hi Onions, thanks for the reply!
Just found a good tutorial that seems fairly straight forward 
http://tronixstuff.wordpress.com/2011/01/19/tutorial-arduino-and-gsm-cellular-part-one/
Its using the sparkfun module I think, which is a bit pricey.
Just been checking ebay and they have modules from china for a fraction of the price like this one http://www.ebay.co.uk/itm/Arduino-Wireless-GSM-SIEMENS-TC35-SMS-Module-UART-232-/320771809651?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item4aaf7d6173#ht_6452wt_1163 . Trouble is I don't think the documentation will be up to scratch and being new to this kind of thing I'm not sure I could cope with it lol, or would it be similar in useage to the sparkfun module?
I'm fitting the whole alarm system so I'm pretty much switched on with how it will work, I don't think I can cause any mischeif buy doing this project. There are PTS (push to set) terminals though which I might have a play with further down the line
Thanks