Is there a postcode for deliveries checker module for drupal 7? I'm thinking about using Drupal for a take away (delivery) ecommerce site and was wondering if there is a module that could calculate the the distance between the postcode added by the user and the shop locations (a few) and if its within a certain radius go ahead and allow the user to place the order. Is there such module available for drupal? if not, is there a similar module(s) that could be adapted to it?

Thanks
There's no single module for this, but you can use a suite of modules.  For example, you can take addresses stored in the Address Field module and then use Geocoder to geocode them and save the results in a Geofield.  You can then use Rules to check the distance.

That said, there is no simple way to do this.  In fact, there's an entire book about Mapping with Drupal.