I also think that this is something that you'll need to sort out yourself at your local PO. Be aware that if you've gone past the estimated delivery date showing on the listing you're also setting yourself up for a late delivery defect, which may be damaging to your seller account. You need to set a longer dispatch time to enable you to custom make items.
You'll also need to list items that you're making on a separate business account (you can have more than one account). A private seller is one who is just selling off their own personal items such clothes from their wardrobe, bits from their loft/garage etc.
A Business seller is someone who buys or makes items to sell on. They need to be registered as a business to meet the requirements of UK law. eBay will be providing HMRC with your details anyway as you've sold more than 30 of those memory bears so it's vital to keep correct accounts for your tax return. You can obviously offset more expenses as a business seller, but can't offset any at all as a private one.
Personally, I'd upgrade this existing one (as it has some feedback) to a business account because it has lots of feedback, and would open another for listing your own personal bits and pieces you're selling off. To correctly register as a business seller simply go to your Personal Information in your account and to the right of Account Type, which will be showing as 'Individual' you'll see an Edit option.
https://accountsettings.ebay.co.uk/profile
This doesn't affect your feedback profile or any current listings, it merely upgrades your account so that you're compliant with current consumer and eBay policy.
Create a new private account to list your personal items on. Just sign up again with the same details but a different email address (each eBay account requires its own unique email address).
https://www.ebay.co.uk/help/account/signing-ebay-account/signing-ebay-account?id=4191&st=3&pos=5&que...
So much easier for accounting then.
