Easel
You cannot readily paint with a canvas on your lap - a canvas need to be upright. So you will need an easel.
Again, there are many different type available. Some have a box for paints and brushes with space for a completed canvas in the lid. However adjustable, wooden sketching easels are perfectly adequate, they are generally lightweight, easy to erect and they can support surprisingly large canvases. Folding artists' donkeys, bench - and table - top easels are also worth considering.
Kind of Easels Model:

|