Most people don't specialise until Masters level as you don't really ~know~ a subject until you've studied it at degree level, it's totally normal. It's good to keep things broad and have your options open. Obviously there are Forensic Psychology undergraduate courses out there but it makes little difference whether you do that to start with or just a general Psychology degree and then specialise.
I'm starting a Masters in Forensic Psychology in September, you're right about the two years of supervised practice afterwards but I'm fairly sure you get paid for it. The Doctorate is essentially the Masters and the Stage 2 qualification rolled into one but there's less courses and probably more competition. It's generally much easier to get onto a Masters than a PhD as funding comes from SFE rather than the university itself so it's less of a risk for the department.
Can't say much about Clinical but I do know it's very, very competitive and most people need at least a couple of years experience before being accepted onto the course.