Thank you for your replies but most of these suggestions are not what I am looking for.
They may however help someone asking in the future.
I think I am going to go with these (the one's I mentioned with a free sim)
http://www.dealec.co.uk/acatalog/gs...-gsm-ad.html?gclid=CMTmzoDjjL0CFagBwwod-5oA1Q
It says it's a Giff-Gaff SIM that comes with it. (Giff-Gaff uses the O2 network).
Calls and texts will only be free to other Giff-Gaff users.
£7.50 a month (recurring) will give you 200 free calls minutes to others, and free unlimited texts to all UK mobiles and landlines. Be careful when the people who it sends SMS messages to go on holiday !!