Well, I was unsure if that was satisfactory on the battery, so I got a friend to come round to give me a jump start.
Still clicking, just the same, and the reading from the battery is now 12.5v dropping to about 12 when trying to start.
I cant even find the bloomin starter motor to see if the earth / wiring from it is dodgy.
The earth strap from behind the engine block (looking from the top, looks fine, secure, and good (this is where Ive been testing my battery from)
So it's looking like its either
The starter motor
The wiring going to the starter motor / solenoid?
If I call the RAC out what are the chances of them diagnosing this / fixing it (if its a dodgy earth/wiring...I understand they wont change the starter motor