Whether you get on the course on not will depend on your TA trade and a strict priority bidding system is used which may explain why you haven't got a course (i.e. someone needed it more than you). Other factors to consider are do you regular fail to turn up to training? do you cancel yourself from courses at the last minute? All these are reasons your instructor may not be falling over himself trying to help you out.
It sounds as though you just want the course for your civi employment, if this is the case why should the MOD pay for it?
If however you genuinely are being dicked around here are the answers:
C - 7 Days
D1 - 5 Days
+E can be completed with Cat C or as a seperate course - 7 days.
They are at Grantham usually though depending on the dates you may be sent to DST Leconfield.
No they can't all be done together unless you are very fortunate with your course bids.