design wild area network for company

I need to give a suitable Wide area network design for a small research company that currently has a HQ in London and is creating two new branches sites in Edinburgh and Cardiff. The company would like these sites to be networked together with the most cost-effective connections so that data and voice traffic may be exchanged across the various divisions. Due to the sensitive nature of the research, there are also a number of access restrictions required between the sites that are detailed in the attached detailed brief.