Hello. I am solicitor with over 20 years experience I will try to answer this for you.
I assume you have been charged with having with you in a public lace an offensive weapon. The facts you have described amount to a defence. Whether it will be successful depends on whether you are believed by the court or not. If you are a man of good character and if you can find someone to say that they have seen other people using your van then you are more likely to be OK. Is your van used for work? If so, what is your work?
Is the case to be tried in the magistrates or the Crown court? Do you have a solicitor? You certainly need one.
No convictions = good character in a criminal court.
You have a defence whether it will work is hard to say. You must get a solicitor and quickly.