It's great to hear that you have a genuine interest in the subject. As an academic, that warms the cockles of my cynical old heart. If you are really interested in the topic, then go for it. Enthusiasm for your subject is vital if you want to make a success of your university studies. A history training teaches you a huge range of transferrable skills - critical analysis, critical thinking, project management, interviewing, writing, even media production techniques, and much, much more - that are in demand from employers in a wide range of areas.

I'm going to assume that when you say you want to be a historian, you're talking about being an academic historian in a college or university history department. That is a very, very difficult thing to do. First you need you undergraduate degree, then a postgraduate Masters degree (normally one to two years of study), and then a Phd/DPhil (both different names for the same thing - a doctorate in history, normally requiring 3-4 to 7 years research and study, depending on what kind of institution you're in).

And that's just the start. Actually landing a permanent academic job anywhere these days is a very, very difficult task that requires persistence, scholarly publications, evidence of high quality research, teaching experience, public engagement experience, and above all luck. If you do get to the stage of completing a doctorate, you're like to face several years of temporary jobs, post-doctoral research positions (post-docs as they are known for short), or work outside of academia. Now, that's academic history I'm talking about. I'm not able to talk about working in museums, school teaching, or other related fields, as I simply don't have experience of them.

The vital thing at this stage, though, is to pursue a subject you are passionate about and not worry too much about where it will take you. Enjoy your studies, engage with a wide range of topics within history, and then see where it might take you.

Hope this helps, and happy to answer any follow-up questions you might have (if I can!).

Malcolm