I think you'll be fine. Electricians usually don't put different gauge wire in for outlet versus lighting circuits, so that won't be an issue, but you'll need to check if/how the lighting fixture was grounded and make sure that you preserve the grounding capabilities with the new outlet. I'd also do a quick check of what other loads there are on the circuit, just to make sure you aren't subjecting the PJ to sharing with something 'spikey'. The link you provided to the light fitting shows it is rated for 2 x 60w bulbs, so you can be reasonably certain that the circuit can handle at least a 1 amp load, but again, check what else is on the circuit and do a quick addition to see if you're anywhere near to the fuse's capacity. And as already mentioned, you'll need to disable the existing wall switch.
I'm not sure if it is an actual code violation, but our city inspectors frown on mixing outlet and lighting fixtures on the same circuit, but from an electrical perspective I really can't see why this is a problem.