It's been a long time since I've passed my test but I would be confident I'd be able to pass. Maybe I wouldn't do things exactly in the expected way but I feel the most important thing is to demonstrate you are a safe driver. Yes, I have bad habits but I don't think they're so hardwired into me I'd let that slip me up on a test. Heck, there are times I have passengers that just wish for a smooth and non-dizzy ride (esp elderly), I'm able to switch driving styles easily.
Sorry but I think if you're not able to control your driving style and neglect mirror checks, only doing them when you think "you have to ", I don't think you're fit to be on the road as you're a danger to other users. Living in central London, the people drive very aggressively here. You'd be a fool to neglect observation, there's people changing lanes, lurking in your blind spots, pulling out quickly from a side road, no signals, people overtaking you, buses and cyclists and motorcycle users weaving in and out etc. People and things appear out of nowhere, simple as that.
People don't expect you to drive by the book, but you need to be able to take the same principles and form an equivalent in your driving style. Some people complain about the outrageous insurance prices for young drivers but with these kind of examples of bad driving, it's not really any wonder as to why the prices are as they are.