Bluewater is a triangle shape with John Lewis, M&S and House of Fraser at each corner. There isn't a BHS or Debenhams at Bluewater which sometimes surprises some people. I would suggest arriving early and parking in the John Lewis Carpark
If we're going for a big christmas shop we tend to do downstairs, go back to the car to drop bags then do lunch then do the top floor. Some of the shops incorporate both floors (Next, Boots, Zara, Gap, John Lewis, M&S, House of Fraser) so you can get a bit dis-orientated. I'm not a frequent visitor but even though I've been a number of times, I still get a bit lost
There are a number of eateries including a fast food court area (Mc'd's KFC etc) and some chain restaurants (Pizza Express, Loch Fyne etc) and two branches of Nando's. The is also a Yo! Sushi
There is a big boots, a fairly big Next (although not the biggest I've been in), a
Lego shop, H&M was moving locations last time I went. All the usual chains are there, quite a few mobile phones shops, a big Currys, WHSMith, Lakeland, ELC etc. Some of my fave shops there are The WHite Company, Apple Store, Pandora, Urban Outfitters and The
Disney Store has had a gorg re-fit with the prettiest floor in the world

There is also a branch of Hollister and LaCoste.
You'll have a great day, it is big and does get busy. Will is be a Saturday you're visiting?