the difference between the UK and other countries though is that English is the most widely spoken language in the world and therefore you are likely to encounter english being spoken in most countries you move to. I think that it is a consideration to make the effort to learn the language of a country you intend living in on a permanent basis.
When I was 9 we moved to South Africa. There was only one school in the country that catered for visually impaired students and therefore I attended it. It was a predominantly Afrikaans speaking school, and it was a boarding school. so I was sent to a school, to stay, all week, where I didn't speak their language and they chose not to speak mine. Although English was taught as part of the curriculum the children/staff had no need to speak it as there were so few english students. So, as an english speaking student I had two choices. I either:
insisted on continuing to speak english in which case I was unlikely to make friends
or I learned to speak Afrikaans and got on and made friends.
I was fluent in Afrikaans within 6 months. Not only fluent to a degree that I could communicate, but to a degree where, within a couple of years, I did all my subjects in Afrikaans, I did Afrikaans as a first not second language, and when I was 16, on "republic day", I was the only english speaking child, from England, but I was the one selected to read the constitution, in Afrikaans.
I don't see why people shouldn't learn the language of a country if they want to live and be accepted there.