Anyone had broadband installed recently? I have an installation question

Hi all, I did a quick search on this to see if it's already been asked/answered but didn't find an answer, so here goes:

We're UK residents but have a holiday flat in Nice. We want to get broadband installed and looks like the best overall package.

Practical question: do they need to gain access to your property itself to install wi-fi, or is it simply a case of us taking delivery of the router and plugging it into the wall?

Reason for asking: we're only in the flat for two specific weeks over May/June and need to know if we have to try to time the installation for when there's someone in residence, or if it's a remote switch-on at their end (and we just need to connect the router, which could be left at the post office awaiting our collection...?)

Further info if it helps: the property has had a phone line in the past but it's not currently connected. But we do have the correct socket on the wall.

I looked on the website and couldn't find the answer, either in French or machine-translated to English.

if anyone can shed any light on this, I'd be most grateful!