Most people will say le weekend, though there are purists who will insist on saying la fin de semaine.
on sera en France ce week-end (oh[n] srah ah[n] frah[n]ss suh week-end)
the noun week-end is used in France as it was adopted from English, partly because it was somehow fashionable to use a few English words on one's vocabulary, partly because it was shorter and less clumsy than 'la fin de semaine'.
Yes, the possessive form of the noun week is the correct form for 'the end of the week' (the week's end).
This is how you would say it. What do you do on week ends?
le week-end - la fin de semaine
Ayez un week-end agréable or Bon week-end
avoir un grand week-end à tous
over the weekend.
bon week-end
fin de semana
"That was the world this week, see you again next week!"
le week-end dernier