Shipping API integration into a Wordpress site

We require Royal Mail's shipping API integration into our Wordpress site. This will involve a REST API that sends order data to Royal Mail. They then automatically generate a shipping label image which we want integrated into our packing label.

More info can be found here: https://api.proshipping.net/docs/v4/api/index.html

And in the attached guide.

Success in this project is likely to lead to further development work as we require this Wordpress site to eventually be built out into a fully customised Woocommerce e-comm site.