Your potential new supervisor is responsible for finding funding from UK research councils, as you will not be entitled to apply yourself. If they do not feel that the project is suitable for research council funding, then your options are quite limited. You should speak frankly to your potential supervisor to find out what the opportunities for funding are. It is certainly too late to get research council funding for a project starting in October unless it is a departmental quota award (these will also probably all have been allocated by now).
Rather than taking a masters degree you might want to consider working in a relevant research environment for a year. You can search for Masters degrees on our siter site - www.FindAMasters.com. Look for one with a strong research component.