2 adults and 2 kids arrive CDG airport mid morning, we plan on heading into Paris to do Eiffel Tower have a browse around the city etc then head out to our accommodation at Disneyland. What type of ticket should we be purchasing so we can use RER B and RER A plus metro stops along the way?
Also where is the best place to leave our luggage for the day as we cant take it up the tower?
Ticket Mobilis 1-5 zone (it's a day ticket for Paris transit) for each person. This will cover you from CDG to Paris, to Eiffel Tower, etc., and out to Disneyland (Marne la Vallee station) out east of Paris.
I would store luggage at a commercial left luggage service near Chatelet les Halles since you will need to take the RER A from there out east to Disneyland. You can Google for various bag storage companies in that area.
Another option is to store your bags at Gare de Lyon train station, using the station's self-service left luggage service. You can get to Gare de Lyon from Gare du Nord (which you will arrive at for the RER B into Paris), by taking the RER D train to Gare de Lyon.
Gare de Lyon station is also along the RER A line, which again, you'll be passing by when going to Disneyland Paris.