....what a discovery (better late than never I hear you groan!). Skype SMS let's you text for €0.08 from your PC. None of that Arthritis in your thumb joint inducing texting from your phone, just use the keyboard (and get RSI!? Don't worry, I have a safe workplace so it isn't a problem).
You can even drop in your own mobile number so that it appears to the sender that you have sent the text from your mobile phone & they then can reply to it.
Clever stuff, and cheaper than standard UK text costs (unless you get free texts with your contract).