RANT is a good procedures/indications trainer but MS Flight Sim is better as it puts the whole thing together with a normal pilot interface (ie the stick) so you can actually fly approaches and get the visual segment at the end as it is very important to include the outside in your scan near the MDA. Being able to see what 600/800m actually looks like a mile out from the runway is essential to the real life use of the rating as I've seen people go round at MDA just because they couldn't see the runway itself (approach lights leading into the murk in good view though). Approach charts available free from the AIP website.
I use MSFS before my SEP IR renewals putting the actual weather in so I get a good feel for the timings/drift on the day.