I have been off work for three months with a knee injury caused by a clutch problem on works lorry , when the incident happened at end of last year . No one took me seriously . I suffered all through festive season and returned to work on jan but was unable to do much driving of lorry , and ended up having to take all this time off , now I am in debt with rent , struggling to live and don't know what to do next , problem is I cant get help financially because in theory I am still employed

If you was in the USA that sounds like it would be a Workmans Comp issue, but based on your Terminology I am guessing you are in the UK, so someone in the UK can respond to this issue.

Did you inform your employer of this accident? See a doctor?