Supplier near taunton

Hi

I may need your advice but I’m looking for a mortar I can bed 2 blue Lias flagstones onto. I would use it to point in between them as well. It needs to match as near as possible some existing flagstone flooring that’s probably 250 years old which has a medium grain light grey mortar. I don’t need too much. Probably 1.5m2 and a bed depth of 15 to 20mm.

grateful for any suggestions you have and where I could pick it up near me.

regards

David