I am developing a research proposal in order to apply for my PhD in Education and I cannot seem to settle on a topic. My interests range from creative arts education and enter the realms of special/ inclusive education so I am thinking of doing something which is a mix between the two. Probably also good to note that I reside in South Africa so I would be doing my research in the context of the South African education sector.

Any suggestions and/or advice?

There's no reason why you can't combine the two. You need to read research articles in both areas and also look specifically for research which has investigated creative arts in special/inclusive education. If there's nothing at all then you have a clear gap which your research can contribute to filling. It's more likely that some people have already investigated some aspects of this topic and then you will need to look for gaps within it or areas on which to build. Good luck!

Do small literature reviews for both and see if there any gaps in the knowledge. A PhD is at least 3 long years and you really want a project you are interested in. I would spend the time exposing yourself to as many ideas/areas possible and find what actually interests you.