...to worry about moving abroad with 5yo DS?

[yummycake123]

I may have an opportunity to move abroad (would go back to my EU country, I've lived in the UK for over 15 years).
I would move with my family (OH+DS).
I know from experience (I moved abroad young) that kids adapt quickly, but for some reason I'm stressing out a bit about my son. DS is in reception and doesn't speak my language fluently, but I'm teaching him (slowly). He loves school and is very sociable.
If you moved abroad with small children, did they adapt to a new language/school quickly? How did you find it? AIBU to worry?