Hey Steve I've been looking all over the gov.uk website and can't find any information regards lighting and triangles etc. Where did you get this info from. And don't point to the Percy Ware-Armatage Trailer Co website again

Must be official government statements only. Thanks.
I'll get a safety chain sorted out and a bumper or jocky wheel to stop the frontend from digging in etc. It does say that this can be achieved with short safety chain. If it's short enough to prevent the coupling from hitting the deck but long enough to allow propper articulation of the trailer.
It's always best to keep it legal.

Not sure how you can prove your trailer was constructed pre2012 though. And it doesn't say anything about repurposing a pre 2012 trailer.