Accepting offer

I have accepted my offer for forensic science and criminology and foundation year at derby university but due to physical and learning disabilities it may not work out for me as I possibly not able to do most of the practical stuff and I don't want to hold anyone back on the course I enquired about if I could possibly transfer to a different course my second choice is computer modelling and animation foundation year I only asked a simple question then fee days later I got a email from the university wanting me to accept the unconditional offer on the computer modelling and animation foundation year course but I have not responded yet as I already accepted the forensic science offer and got my student finance sorted for that course but if I was to change course as I haven't started yet would I have to cancel my current student finance and really?

Tens of thousands of students switch uni and/or course in the next few weeks, as their grades mean that they don't meet their firm offer and end up going to the insurance choice, and to a completely different uni via Clearing. It is a very common occurrence, and all the student finance folks need to do is to send the tution fee to uni B rather than uni A. In fact, in your case it's the same uni so there's probably nothing to do.
Or does "got my student finance sorted" mean you're paying the fees without and loan and have already paid a deposit etc. Have you called the uni and asked about the financial consequences of switching course?