I think its worth saying also, before I bought my current car at the beginning of january I had next to no mechanical experience on cars. Sure i knew how engines worked etc, but I'd never done anything to any cars. When I grew up I was always fixing my own bikes, and other things so I know how to use a spanner.
The first job I tackled was an exhaust change. not in any way difficult
The next job I did was a gearbox change, that was a bit harder but still not difficult.
If you just take things slowly and read up a bit about it before you attempt anything then you'll be fine.
I now feel comfortable doing any jobs on the car really, such as gearboxes, driveshafts, suspension, brakes, clutch changes, coolant flushing and bleeding. Only things I'm not comfortable doing a few things like fiddling with torsion bars. I'm not sure on doing any internal engine work as I've not had the chance yet, but I'm sure it would be fairly straight forward, with the necessary tools and knowledge.
I am now eyeing up an engine conversion in a few months time, which should be fairly straight forward.
Theres nothing like getting stuck into it, sure read about things on the internet, but theres no substitute for getting in there. I am pretty lucky as I have a lot of garage space to work in, and quite a few tools.
But if you are really keen on learning more about cars just buy an old banger and do some bits and bobs on it. Take bits to pieces, clean them and put them back together again etc.