The British Council run courses on Business English for French speakers:
Business English | British Council France
I see the British Council also have some vocabulary/grammar apps for phones/i-pads - I've no idea how useful they'd be:
Apps for business | British Council France
I'm surprised you have found even one wine-specific course!
There is a very useful book, The Winemaker's Essential Phrasebook, which is like a tourist phrasebook, but is very specific to wine, especially the technical terminology of winemaking: it covers English, French, German, Spanish and Italian. But a quick look at Amazon suggests it's out of print, and second hand copies available through Amazon are expensive. It might be worth it to you, though. It won't teach you how write and speak in English, but it will give you the vocabulary that is otherwise very hard to find in mainstream dictionaries.
Otherwise, with regard to describing what wines are like, I think the best advice would be to keep reading tasting notes here and on the rest of wine-pages, on Jancis Robinson's site etc. Even cellartracker would be useful. You might not find all your wines there, but there'll certainly be similar ones and, you'll be able to see the sort of words and phrases that people are using to describe those wines and compare them to how you'd describe the wines in English.
I wouldn't worry if you use the wrong word sometimes - just look at
this discussion here about what "sappy" means in tasting notes, to see that describing wine is entirely subjective, and a word can mean one thing to one person, and something completely different to another!
Good luck!