Look into 0345 numbers. That's a nationwide local calling service. In the UK, even local numbers are paid for, though most plans give you them for free. 0345 numbers count as locals for the whole country rather than just a geographic area.
Check this out [link to www.numbersupermarket.co.uk (secure)]
I'm no longer a UK resident, but work in telecoms and did so in the UK for 15 years.