Gonna be waay better with new divinycell (Herex etc)
Short version that will work:
Fill foam with epoxy/q-cells (about honey consistency) an scrape off well with squeege so only filling the holes. Allow to cure.
Sand flat
replace divinycell - use epoxy q-cell mix again but a bit runnier this time, and make sure both surfaces are coated, bung in the d'cell then a sheet of plastic over the d'cell, then a piece of cardboard about same size (or tiny bit smaller) and sandbag it. Then tape around the board real tight with plastic masking tape (poor mans vacuum bagging

Once cured, feather out edges of glass about an inch and give it 2 x 4oz glass.