In 2024 a police car in it's fancy phycologicaly inspired blue and yellow livery is a rare sight indeed and a foot patrol practically non existent.
I sometimes wonder what they are all doing nowadays.
"all"? implies there are many out there. You would be shocked by how few are actually out and about.
The livery is not about psychology it is about maximising visibility, especially when the vehicle is stationary on a road at an incident.
To put it in perspective -
More than 30 years ago my patrol section consisted of 1 inspector, 3 sergeants and 18 PC's. There were 5 sections in total allowing for 24-hour cover of a busy 80,000 person town. On top of this each beat had a beat bobby.
18 PC's meant that allowing for leave, court cases, sickness, training and abstractions ( officers borrowed for other duties ) it meant that around 10-12 was normal for a daily turnout. This allowed for emergency reponse and what was known as pro-acive policing. This was another word for patrolling the hotspots, looking for trouble and either nipping it in the bud or dealing with it immediately.
After the financial crash of 2008 and the loving caress of Theresa May, ( who is to UK policing as Beeching was to the railways ), actual on the ground patrol strength was often as low as 4. The inspectors were gone, centralised to save money. Sergeants were 1 or 2 and PC's varied between nominally 8 to12, before accounting for reductions mentioned above. How do I know? - I was there and witnessed it. Proactive policing vanished and became "fire-brigade" policing - turning up when a "fire" ( incident) had broken out because there was nobody to keep a general eye beforehand. It's all down to money, or lack of it. ( Don't get me started on the PR con-trick that are PCSO's).
On top of all this bureaucratic nonsense blossomed, and you could spend an hour writing up a non-crime incident that took ten minutes to resolve.
However, that's all another story.
To answer the original OP, the best thing to do is check the .gov website for the rules. I don't know if NI has different rules from England/Wales, but over here you are responsible for the vehicle from the day you become owner. Keep paperwork proof which day that was, so if anybody does ask about back tax you can prove it is not your problem.
In England/Wales you must do one of two things - tax it, or declare SORN, which is keeping it off road. Check what they actually mean by off-road. Some people live in housing association areas which have designated parking spaces. You will need to check if something like that is allowed under SORN. Some people are tempted to declare SORN and then still use it on the road anyway - a very bad idea and likely to get expensive for anyone who does.
Finally, to the person who implied that MoT's were a niggle, take a look at RTA/RTC death stats. Compare the 1970's with today. Don't just compare the bare total number of deaths, but compare the number of deaths per vehicle mile. Today the roads are much busier but the death/injury rate is far better. Improving the quality/safety of vehicles on the roads by insisting on MoT's is one part of the strategy to improve that