You may be exempt from paying the VAT if you match the HMRC criteria and sign a declaration confirming your eligibility. Goods that can be bought VAT free because of your disability include:

• Vehicle adaptations which allow you to drive
• Vehicle adaptations which help with accessing or exiting a vehicle
• Vehicle adaptations that help stow your wheelchair, powerchair or mobility scooter
• Mobility aids (Walking aids, Mobility Scooters, Wheelchairs etc)
• Specialist furniture and stairlifts 

For any of these products to be sold without VAT a declaration must be signed stating

that:

1. The vehicle must be substantially and permanently adapted
2. The disabled person must use a wheelchair in order to be mobile (The usage of the wheelchair will vary depending on condition) 

A copy of the VAT declaration can be found below: