My understanding is that the new engine project was slated to be procured from the 2015/16 budget. They decided to keep the back-to-flying programme and the re-engine programmes separate (you know, because it is far more efficient to have a whole fleet run through major maintenance twice, and re-train all the crews twice). As a result, the engine programme budget has been lost, and will have to be re-allocated as and when. Probably a good thing. Besides, they aircraft obviously haven't flown the hours they were projected to over the last 18 months, so in theory the moment they're flying in earnest again, the stopwatch will be restarted.
IFAIA, the engine is expected to be a Rotax 912 variant - hopefully the certified 100hp version and a modern efficient propeller. (Would be lovely to have a 914 and get a decent climb rate, but that's probably too much engine management left in the hands of nervous 16 year olds unless they come up with a single leaver option).
You'd think a bit of fuel, oil and water would be 'nothing major really', but the way the RAF/MAA thinks, daily servicing appears to be a minefield for unqualified persons - ie mere pilots.