A few years ago I received a producer and was unable to locate all my documents so went to the police station with only the MOT as that's all I could find. The lady I spoke to said I would be reported for not producing the other documents and to wait for a summons. I asked if I should take the other documents in when I found them but she said it was too late for that and it had to go to court.
I received a summons for four separate offenses of failing to produce licence, failing to produce insurance, driving without licence and driving without insurance. I went to court and they gave me a producer to take the documents to the court's local police station (not sure why they couldn't check them at court). I returned to the court and they dropped the driving without charges but fined me (£60 I think) for failing to produce.
The frustrating thing about the experience was that, after receiving the summons I spoke to a solicitor. He advised me that as a summons had been issued the only option I had was to plead guilty for failing to produce. He also said the time limit on the original producer isn't rigid and that if I'd produced the documents to the station beyond this limit, but within a reasonable time, then the failing to produce charges wouldn't have been raised. The only reason I didn't take the documents in later was because I was told at the station it would be pointless.
I was told when they fined me that they were taking into account that I'd made an effort to show my documents (having shown the MOT cert). It sounds like you're in pretty much exactly the same situation so I'd say you've only a small fine to worry about.