Heavy duty black/ grey plastic (Malvern Link WR14)

Hi I am 'urgently' looking for some black or dark grey plastic sheeting - can be strips (min 2' / 550/600mm deep). Must be heavy duty not thin like bin liners. I did have some, it went missing :( ... perhaps you have had a delivery and it was wrapped in protective plastic or it's left over from a building project? thank you.