Tyrant,
First off, you are correct about the Mega STE not having an RF-out connector, they never had those included and were always, back in the day, sold with either a colour or a mono monitor.
When you do choose a keyboard, make sure you get a Mega ST one as the original Mega STe/TT keyboards can be a bit flimsy. Nick Harlow may have some in stock, since his "takeover" of System Solutions. Alternatively there is also Ebay.de (in Germany).
Congrats on getting the machine btw, they are highly sought after. Even if it is a French machine, the TOS roms can easily be swapped & Nick should have some of those in stock too.
Hope this helps,
cheers,
Rich