uPVC soffit board (Lostock Hall PR5)

I need to fabricate a small boxed enclosure over the soil pipe stub on a WC that was recently replaced, and I need a small amount of uPVC soffit board 24" x 12" like the section in the photo. I'd be grateful if you have any in white, grey or even black that you could spare to save me having to buy a 3m length. Thanks for reading, John