In order to authenticate with a UK VPN, you will need the correct type of digital certificate. This certificate can be contained directly on your computer, or stored externally on another device, such as a portable USB drive. Storing the certificate on your computer is acceptable, as long as you do not share your computer with other users.
Reasons to Store a Digital Certificate Externally for Accessing Your UK VPN
Putting a digital certificate for accessing your UK VPN on an external device is a good idea for situations where more than one user will share the same computer while traveling. It is also ideal when your employee will leave his or her computer in an unsecure location, such as a conference room. Without the certificate, it will prevent others from using their computer to gain access to your resources.