If the hole is in a suitable area you could let in a chopping board using a router to take out the affected area. If you set the router depth to the thickness of a glass chopping board, measure the board then put masking tape down, put the board over the taped area and draw round it, then carefully rout out the damaged surface. Take your time, it's easy to cut things out. It's not so easy to stick them back in. However, if you do create any gouges, they can be filled with adhesive or sealant when it's time to fit the board. PLEASE NOTE: If the glass is clear, before fitting it you can paint the underside to blend with the worktop.
Ken the Cabinet Maker, August 2011
