In reply to h01ly123:
I've done it a few years ago and its an amazing hike, you'll have a great time! The Facebook group is indeed very resourceful but if you don't have access to it I would say.
Pack light. If you're staying in refuges you won't have very much to carry but try to stay light. It's very easy to have regular access to water along the way so no need to carry loads (except sometimes the last stretch where I had to use water tablet sanitiser). Food is also easily accessible, between the small villages you cross and the cheese farms, you won't starve. I also didn't bother with waterproof trousers, just wore shorts the whole time, fine under rain.
Keep your footwear light and change socks often. The terrain is not technical but you do walk a lot, so keep comfy in the heat and you do occasionally cross a stream.
I used walking sticks for the first time on it and absolute game changer, cant hike without them now! Use the cicerone guide which was very complete in my opinion, and rip off the pages you don't need to keep the weight down. Don't bother with a map either, its good for preparation but on the trek, the mini maps of the guide are enough and it's so well marked its impossible to get lost.
You can pay in euros everywhere. It's not as busy as it sounds, never had to slog up paths and you meet fun people along the way.
Have a great time! and for after in Chamonix, I recommend getting your celebratory meal at La Tablée, on Avenue de l'aiguille du Midi, its delicious