It doesn't matter what they accept or don't accept. We've left. If we won't shift at all on their red lines we won't get a favourable FTA and we'll all lose, us more than them though.
To be honest the additional tariffs that will be incurred in the event of no FTA generally will only be a relatively small factor compared to the additional costs due to the imposition of non-tariff barriers which are happening anyway as per the link posted by TLWYS.
Still, there's always our viable walk away option. Now that the spit roasting in store for us from the US and China doesn't look as attractive as originally thought, I'm sure Australia and Kenya will step up and replace the reduced EU trade.