First off, let me say that I have no experience in what I would consider offshore sailing.
That being said, there are much worse choices of a good all around 30 ft boat, but, I'm not really sure what you mean by "offshore".
I'm gonna gamble on a big generalization here; For most people, offshore means going further than, say, 25 miles off the coast for more than 24 hrs with no safe harbors to get into for at least 24 hrs. Farther and longer than that means that you may need more safety gear and more heavy weather experience. You have to face the fact that you could be hours or days from medical attention if injured or sick. Traveling in a boat that averages 5 knots means that you have to be prepared for weather some of us would could not imagine dealing with.
Can the C&C 30 MK I take a beating? Hell yes. More so than many boats.
Can it cross an ocean? Yes.
Is it ideal for crossing the Atlantic? Probably not ideal.
For a short coastal hop, the most important issue after the condition of the vessel is your weather window.
Sailing down the coast for a few hours to the next harbor is not what I would call "offshore" and I think many would agree.
You may find that sailing out on the ocean is kind of boring compared to having rocks, islands, beaches,buoys, currents, and other boats to make things interesting
edit: did not see your next post until after I posted this. I think your plan is pretty solid.