If your problem is indeed with the castoring nosewheel (which means, in case you didn't know, that the nosewheel is free to rotate, and you have to steer the aircraft on the ground with differential braking at low speed, or through aerodynamic forces on the tail at higher speeds) then don't think it'll be solved by going to a Diamond Star. It's got a castoring nosewheel too.
If it's just a matter of not being able to reach far enough for full deflection, then before your next flight spend some time adjusting the seat and/or rudder pedals (one of them will be adjustable in any case) or experimenting with additional cushions, either under your bum or against your back. 1.7m is not extremely short and you should be able to adjust your seat so that you can reach and see everything, even without additional cushions.
Remember (or write down) the adjustments you made/cushions you used, because flying, particularly landing, is done by eyesight, mostly, and you've got to make sure that the picture from your seat is the same at every flight. In fact, some airliners have indicators in the cockpit which pilots use to adjust their seats, so that their eyes are exactly in the place the manufacturer intended.
And as far as the MOT is concerned... Planes that are used for flight training are checked every 50 hours flying. For a typical flying training plane, that's every few weeks. And such a 50-hour check is way more thorough than the MOT. Not to mention the 100, 1000, annual checks and the A-check you perform before the first flight in the morning.