You're right, you dont need a degree but it would be advantageous. Its a difficult job to get into, try getting a normal job with your local police force and work at it from the inside it may take some time (took me 5 years). Some forces have Forensic Vehicle examiners which is a SOCO job but just for Vehicles or Volume crime Examiners. These are sort of the first rung on the ladder. The FVE jobs are home office funded until 2006 and there are always jobs going as the previous person has moved onto a SOCO/CSI role. These give some valuable experience and sometimes almost guarantee progression, depending on job availability.
Also get into photography (not digital SLR) this will be a bonus and is an essential requirement in some forces.
Good Luck.