I agree with HazeandAlan.  I pay about £25 per annum for the Skype service they mention.  I use it for all my UK land line personal and business calls.  I also have a UK land line number as part of the package so people in the UK can call that and it comes up on Skype.  They just pay for the UK call.  You only pay extra for premium lines and mobiles but it's not a bank breaker.  If you need to call premium numbers (0845 etc.) from time to time, you can often find a normal number on Say No to 0870 web site http://www.saynoto0870.com/