Open Minecraft, and make sure that you are logged into your Microsoft/XBOX account.
Select Play
Select Servers
Select Add Server
In Server Name enter a nice name like LGMC, or London Gaymers
In Server Address use play.mc.londongaymers.co.uk
Leave the Port as default 19132
Select Save
Now you find the server you added on your Server tab.
Select it
And then select Join Server
You won't need to add the server every time, as it'll be saved, and you can just skip this step.