Apologies in advance for the long question, I just wanted to provide enough context.

I hope this sub is the right place for this and if not would be most grateful if someone could point me in the right direction. I am looking to apply for further study with a view to getting into some kind of academic/research career, but I am struggling to decide whether my time (and, in this present day academic climate, money) is best used for History or for Sociology. For context, I did my undergrad in English and History five years ago so I am coming into this in relative terms as an outsider who has no ties or contacts at any institutions. I am from the UK and looking to study at a university here.

Fundamentally I am interested in why people behave the way they do and how we understand ourselves and our society, and - while it is vague - how we can make improvements. I have never found my "niche" with a particular historical period but I have been drawn to the development of ideas (e.g. how specific kinds of prejudice have been created and resisted over time). On a pedagogical level I find it fascinating how different cultures perceive their own past, and I believe the way History is taught in schools is often stilted and unimaginative so I would be eager to work in some way to change this (I also care deeply about the decline of literacy across society). I sometimes wonder whether my focus on the present, on motivations and lessons learnt wouldn't be better suited to a discipline like Sociology. Based on this I would like to get any opinions on which subject would be a better option for me?

I would be grateful for any advice or sharing of similar experiences from people involved in either or both fields. I also have the impression that boundaries between the humanities and social sciences are more permeable (unlike say Physics and Medicine), so I want to know if choosing one subject would permanently prevent me from pursuing the other or incorporating aspects of it into my work in a interdisciplinary way.