eg: France is across the sea from UK.

is this a well worded sentence to describe the geographic location of France as opposed to the UK. if not, pls. kindly suggest a better one.

Isn't France across the English Channel from the UK?
Yes, indeed.

Vincent sat across the table from me.
The famous painting hung across the room from the sculpture of Venus.
My cousins live across the river from my home in the country.
Across the lake from the cottage there was a mysterious old barn.

Teachers: We supply a list of EFL job vacancies
oh, yeah. it's English Channel. but just take that channel as part of the sea.

according to what u said, it seems that in the first query, it is fine to collocate across with from.
 CalifJim's reply was promoted to an answer.
Students: We have free audio pronunciation exercises.