This custom is not limited to weddings. Many Slavic governments use this tradition when greeting diplomats and people of political importance. Joe Biden even got a taste of it on a recent trip to Ukraine.
At a wedding, this custom can take one of two forms. On the one hand, the hosts of the event (usually the parents of the bride and/or groom) can welcome the newly wed couple with bread and salt upon their entrance to the reception.
The other option is for the hosts of the event to stand outside of the reception space, and welcome each individual guest by extending the bread and salt to them. This is the version that the Puddings will most likely be incorporating.
This is by far my favorite Polish wedding tradition, and it is an easy one to incorporate into a wedding reception if you are looking for a nod to your Slavic heritage :)