0800 calls are free from UK landlines. They are often chargeable from mobiles and require the caller to drop the first zero, so our number would become 800 098 8079. A better option is the 0333 number.
0333 calls are national rate numbers, equivalent to 01 or 02 numbers. They are typically free from mobiles as they are included within call plan minutes. This means that it will cost no more than dialling a Leeds or London number.