Finding a PhD

Now this is something which is at least 8 years away for me right now but I've been looking at how you get a phd as it's always been a dream of mine to get a doctorate but from what I've found you don't apply to the uni but a lecturer who gives you a PhD from the uni they are currently working at. Do I understand this correctly and how do I go about finding such tutor?

You don't need to do this now; all you need to be thinking about is what kind of area of psychology (im assuming psychology since its in this forum) you are interested in and keep interested and reading in it. A PhD isn't a "taught" thing, you do research, so you need to an eligible PhD superivisor to do a PhD with. Basically, to find a prospective supervisor, you can find their academic webpage on the university website and it will say (interesting in PhD applicants) somewhere. Then, you draft a research proposal with the supervisor, and then the university will examine a pool of applications then decide which are the best, which ones to allocate funding (or if you are self-funding then this won't apply) for you projects equipment and your salary, etc.

You don't need to apply to the same university for undergraduate and post-graduate, either, so it shouldn't really affect your decisions for now... hope this helps