How will you know when you're due for testing on your tank... Will the transport department send you notice that it's required for next registration?
Either replace it if necessary, but it is over 10 years mark. It’s needed every 10 years, but it’s a waste of time to test it if you aren’t going for a RWC/selling.
Can the police put the car off the road if it’s out of date?
Most don't have a clue anyway lol. But, your responsibility is to check the compliance date on the tank.
Tank inspection is vital and it is foolish to ignore it. Unfortunately, areas around the sub compartment in the case of the externally mounted tank, can get packed with dirt and rust out the tank. Another area is the underslung tank with the stone shield. You will get no warning, the tank will split at the weak point and the contents will instantly turn to gas and can severely damage the vehicle with its explosive change of state. It is wise to have a look at your tank periodically and if you are off road, often for your own good. You have never done anything wrong until it goes wrong. But I have seen a brand new Toyota destroyed by a fault in a seam weld. The tank opened up along the seam and the floor wound up half way up to the roof. Nobody got hurt but the car was a wreck.