I found too late that was the case, i found it was that way too with regards clerks and money that could be claimed. It wasnt until we got a new Clerk Sgt into my troop who told us and helped us claim, we were given money for paper (and our job obviously) almost every week. Top bloke.
If you're interested in OU study, it's well worth looking at the funding that's available - just assuming that you're not entitled may be a mistake. The support varies depending on where you are (Wales is particularly generous) and, I believe, can "only" be claimed for 6 years of study.
As an example, someone living in England, with a partner and one child, and studying courses worth between 30 and 60 points (probably the most you could realistically tackle while serving) can get FULL funding if their gross household income is up to £19.7k and partial funding with up to 33k household income.
Also, if you receive a full fees award you automatically qualify for a study grant of £250. This can be claimed every year while you're studying up to the 6 year limit.