Good advice from @jonatjonatjonat
I can only see one of your items with free postage/seller pays and that is a fairly pricey tracksuit.
All I will add is that if the item is sent as a parcel at the Post Office, you will get proof of posting and confirmation of delivery even if you use stamps.
However, it would only be covered for loss/damage for up to £20.
"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)