We used to use an 0800 no but have stopped using it now, partly because more and more traffic comes via smartphones and as said before it cost to call these nos from a mobile. The other reason in having a geographic number rather than non geo imo is it instills some initial trust and helps locate your business which could make the difference in someone calling or not calling.
If you are getting leads via a website having an geographic number and address helps with google maps, showing your local to the client and establishing trust. There is some stuff from ofcom below:
Consumers know what 01 & 02 - local or geographic numbers - are and believe them to be the cheapest number to call
Consumers think there is little difference in cost of calling 0844, 0845, 0870, 0871
Consumers are less likely to call numbers that they perceive to be more expensive to call and/or are unfamiliar to them.
Crucially, 65%-78% of consumers either won’t call, or are unlikely to call, telephone numbers used in adverts if they use these types of numbers: 0845 (65%), mobile (70%), 0870 (73%), 0844 (76%), 0871 (78%).