PHP lat & long distance measure then generate web page

I have a postcode search on my website already: [login to view URL] But I am changing it and I need someone to build a new postcode search results page. In my database, I have latitude and longitude of all of my locations and the customer's lat and long is in the URL (can be seen in link above). I need someone to calculate the distance between the customer and the locations and show them the closest 5 locations. If the customer doesn't have any locations near them within 30Kms, it just shows the customer the bottom module which says "We don't have any camps near you (yet!). It doesn't show this module if there are camps nearby. I have already created a HTML template page which is easy to use, you just need to convert that to PHP. You should use the CSS included in the [login to view URL]