The most convenient way is to register on a student exchange or host platform where you can put the direct price of your accommodation, the dates that suit you, or if you want to do an exchange, your needs and preferences.
Nowadays with the internet and social networks it is very easy to get to know your host and guest families in advance.
In the United Kingdom there is a documentation that proves your legality and criminal record. Not all countries have it, so if you want to be a host family in the UK it is important that you have this documentation.
Students who go to the UK to learn English appreciate a warm, empathetic and friendly family that helps them to find their way around and makes it easy for them to live together.