can I use my road bike off road?
There's a whole sport - cyclocross - that involves riding road bikes off road. Typically the gearing is a little lower than a stock road bike, and these days a lot of them have disk brakes. Most will take fairly wide tyres, 38mm is not out of the question.

For riding a stock road bike off road, I'd look mostly at tyres. If you can find some that will clear your frame that have a bit of tread that will help a lot. Puncture resistance may also be worth while, you're more likely to find thorns off road. I would also experiment with lower tyre pressures, as that may improve traction.

Other than that, I'd just ride and see what happens.