I've held a license for near 20 years but my actual driving experience is a lot less - but I'm still not in a rush to drive on roads I don't know, etc. I don't generally worry about speed limits as 90% of the time it is signed and there are some fairly common sense things that clue you into the likely speed limits such as street lights that you will pickup on over time. But personally driving in terms of observation and theory (I'm a practical learner so doesn't matter how many times I read the highway code, etc. it doesn't stick until I've had a real experience to work with) doesn't come naturally to me so even after all these years I still don't feel perfectly comfortable that mixed with how many inconsiderate or just poor drivers means I tend to try and avoid busy times and/or use lesser used roads, etc.
One of the big things for people like myself and probably OP is understanding the difference between looking and seeing (discriminating what you are looking at) the thing that kind of was an epiphany so to speak for me in that respect was driving around and looking at the lines in the middle of the road and noting what they actually were as they changed - after awhile I was actually looking at things like signs, markings on the road on approach to roundabouts, etc. for the information that was important to me, etc.
EDIT: One that kind of shook me recently - was joining a dual carriage way and due to 2 road closures and an accident pushing a lot of traffic that way as a diversion it was packed - lane 1 had no spaces between traffic which was solid as far as the eye could see infront and behind moving a good 60 mph and too many vehicles in lane 2 for anyone to realistically pull out to accommodate me and the immediate few drivers who could have done something to let me in just sat there making no attempt to do so - first time ever in that situation where adjusting speed to match traffic/gap in traffic didn't have an obvious result that didn't end in a collision and for a moment my brain just kind of froze - fortunately before I had to make a decision about coming to a stop on the slip road which is a nasty position to be in really someone slowed right down to let me in.