Another option could be to train as a mental health nurse first. If after that you still want to become a clinical psychologist then you can take a BPS accredited postgraduate psychology conversion course which takes 1 year full time (and part time options are available). The conversion course qualifies you to apply for the clinical psychology training programmes, and also allows you to build up relevant experience from nursing, but with the security of a nursing job should you be unsuccessful in applying.
Look on the British Psychological Society's accredited course search for conversion courses.