0% Medical Products (VAT Relief) For Supplies sold on Amazon

Hi I sell a number of medical supplies (for disabilities/for the chronically sick) that my customers should be able to purchase without VAT by declaring their situation. On Amazon there is no way for 3rd party sellers to give customers a declaration form and there is also no real way of refunding them the VAT only, after the sale has taken place. Either the customer pays full 20% VAT or I can leave a very clear notice stating that the item they are buying is 0% VAT and it customers are self declaring they are eligible by buying the product. Will this kind of notice suffice so that I can sell my supplies at 0% VAT for the customers I know (often desperately) need my supplies fast (with 1 day prime delivery).

Hi Anthony P,
Please contact the VAT disabled reliefs team here:
Charities and Community Amateur Sports Clubs
For further guidance regarding the requirements for eligibility declarations on the goods that you are supplying.
Thank you.