Which public order offence?
You don't have to attend a voluntary interview but if you have a defence it is generally a good idea to do so.
The only real benefit in not doing so is that if you have no defence and you cannot answer questions for that reason then you would avoid the adverse inference in the no comment interview.
If you don't they will either just arrest you or summons you to court.
If you can deny it then you should really be doing so.
Can I clarify anything for you?
They can arrest you at any time.
They are just offering a voluntary interview to save on labour.