Well done EY! I think it's great you're riding to work.
You are considered a vehicle so you have to follow the rules of the road. On some roads there are cycle lanes but they are inconsistent and may just end without warning. Basically, it is taking your life into your own hands, riding in traffic. Best be safe and find less travelled routes. DH rides almost exclusively and this is what he does. He finds it a bit scary in traffic. And about round abouts - yes it is safer to be a part of traffic than try to cross as a pedestrian. Also, GET A NEON REFLECTIVE VEST so that you are very visable on the road. If you have anymore questions about bicycle commuting, just ask. I live with an expert.
If you are in a lane and it is narrow, take the whole lane. Don't put yourself at risk by squishing over to the side where cars are parked. the cars will pass you when it is safe to do so. Riding in traffic takes a certain amount of agressiveness but you'll get the hang of it soon.