The full guidance is contained in HMRC manuals VATSC 51620-53530 and can be accessed here. Please note that some aspects of it are yet to be accessible.
There can obviously be no definitive rules in respect of grants and contracts and this is just HMRC guidance which cannot cover every possible scenario. However, there is certainly better commentary in respect of:
It also provides commentary on all the important Court Decisions which have covered the topic.