How do you return an item (for a refund) on Amazon's UK website without a printer?

I ordered an item of clothing based on my usual size and it's swimming on me - it's far too big

Normally, if an item was 20 euros or less, I'd just give the item away to a relative or a charity shop - but this cost me 80 fecking euros

I've never actually had to return an item before - so how does this work without a printer?

I'm in Dublin if that means any difference of dropping it off to a drop off point they have?

Also, like, how do I pack this back up again for posting? I've ripped open the package bag it came in

And who pays for the re-packing and postage etc

After I add the reason for returning, I'm getting:

"Receive an Address Label .... Varies

Use any delivery service that is convenient for you, or coordinate return delivery with the Seller.

Printer required – print the label at any time from Your Orders. We’ll also e-mail it to you."

I've no printer, so it looks like "Use any delivery service that is convenient for you" is the option

But what delivery service? Who is paying for this?

It doesn't show me these options and "Confirm your return" is the next button to click

I don't want to confirm it till I know what's going on here

Sorry in advance, I think I'm missing something basic on the website or I just need more coffee