Postage Policies - Entering that in HELP AND CONTACT at top of page gives all you need -
https://www.ebay.co.uk/help/selling/posting-items/setting-postage-options?id=4089&st=3&pos=1&query=S...
Postage is simply a matter of getting a booklet from Post Office “Our Prices” all information is in the booklet. Avoid getting involved in any ebay postage unless you are sure that information provided meets your requirements, as postage quoted on listings is what the buyer pays, and if insufficient you cannot ask buyer for more, and have to stand any extra expense yourself.