Hi Simon,
I'm no expert, but here goes. Roughen the PVC pipe to get a key, and try some polyurethane glue. A little experimentation would be prudent. As for primer, my guess would be an etch primer. Epoxy will tend to find it's own level to some extent, so I'd be inclined to use a 2 part wood or car body filler, or maybe some form of caulk, depending on the intended purpose.