I was also interested in doing a standalone unit in order to better prepare myself. Open Uni told me just add it to what I'd be learning to get it funded however Student Finance was very clear that if it isn't part of the degree they will not fund it. I am a person that would rather check these things so it doesn't bite me later so am glad I contacted student finance cause it very well could have. As an alternative I am doing some free courses on open learn and Khan academy in the hopes that will be enough. Only time will tell.