Will I lose my training contract if found guilty?

I have a training contract at a top ten firm, commencing in 2 years time. Unfortunately, I was recently involved in a diasagreement with a public servant which resulted in my being arrested for a Section 4 public order offence.

I intend on pleading not guilty as I dont believe I committed this offence.

I intend on informing the SRA if found guilty, allthough I have been advised that this is unlikely to prevent me practising.

I have no prior convictions of any sort. I have exemplary work experience, pro bono and academics. This is clearly an isolated incident and entirely out of character.

How do you rate my chances of keeping my training contract? Should I disclose this to them immediately or prior to commencement of the training contract?