You are selling multiples of new items on your account so should really be registered as a business seller.
Business sellers do have to have an 'any reason' returns policy and will pay Ebay fees for listing and selling.
However, you would not have to use Simple Delivery.
If you also sell unwanted personal possessions, you can have an additional private account.
https://www.ebay.co.uk/sellercentre/selling/create-ebay-business-account
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)