Base insulation entrance forecourt - in the ground or not

Hello everyone, as preparation for the facade, I am having a base insulation installed. At the entrance, the effort to insulate 30-40 cm into the ground is relatively high and I am not entirely comfortable digging at the old foundation. Inside there is underfloor heating, outside strip foundation. Should I still go ahead with the effort over the 5-6 meters or can the forecourt be paved (interlocking stones) and the 20 cm base insulation be installed from the ground level at that spot? Thanks and best regards