The distinction between 'local rate' and 'national rate' calls was abolished many years ago. It now costs exactly the same to call your next door neighbour as it does to call your granny at the other end of the country.
All phone providers offer packages which include free national rate calls but, inevitably, they tend to be far more expensive than those packages where you pay per call. For example, Shell Energy have a 'Fast Broadband and Anytime Calls package for £29.93 per month. However that's much dearer than their basic Fast Broadband deal, which costs just £17.99 per month.
The cheapest way to get free (or, more accurately, 'included') national rate calls is probably to use a mobile phone instead of a landline. For example, Asda Mobile offers a package including unlimited minutes and texts (plus 3 GB of data, if you happen to need it) for just £5 per month.