Quote from today's Daily Mail
"Remember to brush up on your rights
If you buy online you are entitled to a 14 day cooling off period. This means you can return the item within this time frame (starting the day after you receive it) for whatever reason & get a full refund.
This includes the cost of postage when you send it back." etc, etc.
Quoting the Daily Mail is laughable, you may as well quote the bloke in the local takeaway. The actual information is freely available.
The distance selling regulations have been superseded. They no longer apply. The Consumer Contracts Regulations are now applicable.
https://www.legislation.gov.uk/uksi/2013/3134/regulation/34/madehttps://www.legislation.gov.uk/uksi/2013/3134/regulation/35/made
picking relevant parts out of the actual legislation:
34.—(1) The trader must reimburse all payments, other than payments for delivery, received from the consumer, subject to paragraph (10).
(2) The trader must reimburse any payment for delivery received from the consumer, unless the consumer expressly chose a kind of delivery costing more than the least expensive common and generally acceptable kind of delivery offered by the trader.
(3) In that case, the trader must reimburse any payment for delivery received from the consumer up to the amount the consumer would have paid if the consumer had chosen the least expensive common and generally acceptable kind of delivery offered by the trader.
(4) Reimbursement must be without undue delay, and in any event not later than the time specified in paragraph (5) or (6).
...
35.5(a)
The consumer must bear the direct cost of returning goods under paragraph (2), unless—
(a)the trader has agreed to bear those costs, or
[note there are other exceptions, but they will not generally apply]
There is more to it than these couple of extracts. Many retail's terms and conditions are more generous and will bear the costs of return postage
if that is heavy going, Which simplify it, Distance Selling Regulations (this is the out of date stuff that could be found by googling and links to the new regulations) Consumer Contracts Regulations
I wouldn't rely on the daily mail for anything- I once saw it described as a bile filled hate rag which I think was about right, although the mainline comments section is entertaining to read at times.