Romans

Well...As far what I can see on the letter from police... "bla-bla-bla...without third party insurance Contrary to section 143 of road traffic act bla-bla-bla..." My insurance is Comprehensive...I'm totally lost here

Hi there everyone. I was stopped by police in London.I've got smaller number plate.Basically that's not a big issue(not very important for now). But was is important,is that He said I don't have an insurance,even it was showing on his tablet that I have... Basically he decide that that I was going from work to home but My insurance stated "SDP only"... Any advice on that,please? P.S.Also,they stopped Me because on small number plate...But how they can see it from the front??? So I ask that question...He replied that "an officer from down the road told him about my number plate"... it is all recorded on camera,our conversation I mean... Question is ...Is it legal for police to put someone "in the bushes" and then report future to the road about something? Any advice on this also,please? Thank You Best regards