Brexit - Different policies on the single market and customs union

There are now clear differences between Conservative and Labour policies on how the UK should trade after Brexit, with Jeremy Corbyn saying there should be a customs union with the EU and Theresa May taking the opposite view.
Daily Politics reporter Emma Vardy and Prof Alasdair Smith from the UK Trade Policy Observatory look at how Brexit could affect shopping bills. Put simply, it seems to depend on whether the goods come from within, or outside, the remaining EU states.