Hi, I don't know about Poly-C directly but I see no harm. Personally I use a primer or sealer or something like resin to seal the grain -rub it back then either spray pain,humbrol tinlets or Tamiya acrylic paint.
I was a big fan of halfords paints -but not recently (I think they changed formula-I've had problems even with car parts recently). I was a big fan of Krylon plasti-kote spray paints but they're not as easy to get hold of these days. I would say avoidplasti-kote "acrylic" brushed enamels -they're not "enamels" like they used to be,the "acrylic enamel" pot I used recently was like yoghurt and took 2 weeks for it to dry. Humbrol seems to have dug itself out of a bit of a hole last decade -I've started going back to it,but brushed (I can never seem to airbrush it). Tamiya acrylics I've loved for years, brushed or airbrushed, but found their rattle cans -particularly their primer utterly and completely awful.
....best is to experiment yourself I think. Everyone likes something different. Just make sure you're not mixing things incompatable -I must say personal experience these days is that's not as easy as it used to be.
Rich