Tim2sms summed the situation up in his last paragraph – If in doubt get professional help!
The logic of using a UK account is straightforward: set up a DDNS service and then access the UK account through a Draytek router with VPN facility. The reality is far from uncomplicated. Setting up the DDNS account is not a problem: after setting up the account the next step is to permit access to it from the overseas computer. In attempting this I followed the guide on the DynDNS website: What is Dynamic DNS? What can I do with it?” (http://www.dyndns.com/support/kb/dyndns.html#whatis).
The next step is to set up port forwarding (Called Port Redirection in the Draytek Setup) and here one comes up the inadequacy and incomprehensibility of the Draytek User Manual, which provides no straightforward explanation. During my web research I encountered IT professionals being stymied at this stage, and waiting for over a month without a response from Draytek.
I entered into what I believed to be a straightforward process, but have now become stuck. To cut to the chase – Has anyone in this thread successfully set up the Vigor 2820n router so that it can be accessed using a DDNS account?