Making a secure connection to your UK VPN is important anytime you are traveling outside of the United Kingdom. Without a secure connection you run the risk of hackers and other unauthorized users gaining access to your resources. However, you are able to take steps in order to ensure only your employees can connect whenever they are abroad, such as using two factor authentication.
In Order to Access Resources within the United Kingdom You Need a UK VPN
When you do not have a UK VPN connection your users will be unable to connect while they are traveling outside the United Kingdom. This is because the UK requires certain resources to only be accessed from inside the country. The only way around this requirement is with the proper VPN connection. As long as your users are authorized to make this type of connection, they can access resources on servers contained within the United Kingdom.