I wouldn't go with a full wetsuit for kayaking, a farmer john style wetsuit is less restrictive.
For years my boys (13/16) used farmer john wetsuits (3mm) with a .5mm long sleeve neoprene skirt (ie. NRS kidskin, or Hydroskin) with a splash jacket or semi-drytop. I liked that the NRS farmer johns have padded knees, most of the kayaking/rafting we did was on shallow rocky rivers in Colorado.
As they became better and more confident in kayaking, they switched from the farmer john setup to the NRS hydroskin or similar pants, and either a thick skin fleece top or neoprene top covered by a drytop. They found the pants were quicker/easier on/off than the wetsuit and less restrictive.