MSFS, if properly equipped and used within its limitations, can indeed be a tremendous help. I had a forced hiatus from active flying for a few years but was actively using MSFS in a professional capacity all the time through this. Coming back to flying after that was much easier than it would have been without the constant exposure.
Some important things, I think. It is vital to have proper flight controls to use. Secondly, it makes a lot of sense choosing an airplane (possibly an addon) which as closely as possible corresponds to the one used in real life training, so you can actually incorporate the original checklists. For light planes, Carenado makes a few of them to a fairly high degree of accuracy. It's also possible to get a working GNS430/530 system in your sim, there is one available via RealityXP. It uses the original Garmin simulator but allows to use the GNS as a gauge, as opposed to the rather bad representation of the Garmin 500 which comes with FS itself.
For IR training, most of the time the default scenery will work fine. If VFR navigation is part of the curriculum, there is a series of full photographic representation of the whole UK, Germany and Switzerland. For the UK, this certainly helps. Also there are lots of UK airfields available both commercially and freeware, Alf Denham's stuff is available on Avsim.com. I personally found it quite interesting to "fly" VFR cross countries in the Sim with a high fidelity scenery before setting out on the real trip, simply because it will buy you capacity. The photosceneries are pretty good. Likewise, you can have a look at unfamiliar airports and it's surroundings if the scenery is good enough.