When you say "I do law", do you mean that you're applying for a Law degree? Or do you mean you're doing A level Law?
When you say "extended diploma in crim", do you mean the WJEC Level 3 Applied Diploma in Criminology? (There is no BTEC in Criminology, unless you mean Forensics and Criminal Investigation.)
Knowing exactly what you're studying is incredibly important. UCL specifically say on the same page I mentioned above that:
"The WJEC Level 3 Applied Diploma in Criminology is only accepted for entry to the BSc Crime and Security Science programme, and the Engineering Foundation Year programmes. This qualification is not accepted for any other programme at UCL."
What course we're you hoping to apply for at UCL?