Is it possible to terminate a PhD during the first year and begin a different one the following september?

I currently have a BBSRC CASE studentship but its not going well at all and I feel im better suited at working in another area.

It is possible to do this, but you can't just transfer, you'd need to find and apply for a new PhD studentship. Although, to the best of my knowledge, the BBSRC have no policy to stop people receiving a studentship after leaving one for reasons other than ill health, it may be difficult to find a new place if you're already planning to give one up (your potential new supervisors may consider you a risky prospect).

You should speak to as many people as possible to address the problems you are having with your current research. If you're not comfortable about speaking to your supervisor then speak to your appointed advisors or the departmental postgraduate tutor. If your project is not going well then it is up to these people to make sure things begin to change. In a worst case scenario, if your problem is with your supervisor and not the research itself it may be possible to change to a different supervisor, within the same department. If it's the other way around, then your supervisor may agree to change the direction or focus of your project to areas which suit you better.

You should consider that you have only been in the lab for 5 months. It's not unusual for research to go slowly and sometimes things just don't work.

If you give up within a year your supervisor should be able to appoint a new student the next year under the same grant. If you leave it longer than this then your supervisor will probably loose the grant.