The room is expected to include soft furnishings, low-stimulation lighting and sensory-friendly features.
Janey said when Ben had to go through “invasive procedures which were obviously quite overwhelming, there wasn’t that many places to go to get away from other people”.
Ben’s father David is preparing to run the London marathon and the Bath Half marathon to raise money to adapt an unused space at the hospital.
He said there is a “real need” for a “place where children can relax, where you can have meaningful conversations”.
“It would have made our experience and Benjamin’s experience at the hospital a whole lot easier,” he added.