If you are following Scrum and Agile principles, you need to keep doing that. What I mean by that is that some people will have a tendency to give up on certain desired things just because now they are harder to have when working with a virtual team.
For example, you might be tempted to skip the daily standup and transform them into a larger, once per week meeting because it's easier (especially if you work on different timezone), and because it's no longer a standup, but a sit down behind a laptop screen. And this can happen with other things that were easier to do in person. You need to keep doing the Agile practices but think how you can achieve similar results with distributed people.
You will rely more on tools and technologies, and you will probably also need to be careful when selecting them to facilitate the work. Additionally, you might have to go through a few tries before finding something that works nicely. For ex, you might discover a physical whiteboard that offers maximum flexibility will need to be replaced with a more rigid tool that makes it harder to achieve the same result. Do you still try to go with as similar result, or do you give up on the result you want and just fall into the way of working that the rigid tool imposes?
That's the way you need to adapt. Think what result you want, then see how you can achieve that given the complications of having a virtual team as opposed to a colocated team.
With that being said, there are some other considerations to keep in mind, that don't relate to Agile or Scrum, but to the fact that you now have an external team. I'll mention a few big ones of the top of my head, but you will need to pay attention during reviews and retrospectives to spot others.
Us vs Them
This mindset can creep in when working with external teams. We are the brains, you are the muscles. We make the business decisions, you handle the execution. It's our project, you just work on writing the code. You need to pay attention to this kind of behavior and make sure it doesn't happen. There needs to be team ownership on the product that you are delivering, even though you have some people in the UK, and other some place else.
Cost vs Quality
You don't mention why you went with an external team in another country. Could it be in order to reduce cost? There is often a strong relationship between cost and quality. Make sure you are getting back also the desired quality, not just a reduction in cost.
Image vs Value
Following on the previous point, make sure that the team is generating value, not just present an image that things are going in the right direction. Sometimes, external providers put too much accent on a good relationship with the client and paint a positive picture, even if that means sacrificing some aspects of the product.
You didn't mention where the external team is located. If there is a large cultural difference between your in-house teams and the external teams, this can cause all sorts of misunderstanding, assumptions that then prove false, or affect the collaboration in weird ways. See for example the power distance index.