FOI deals with information that is recorded electronically. If the information is not recorded electronically then there is no obligation to release it under FOI.
Where information is recorded in a format that differs from that in the demanded answer, and the expense of reformatting it would cost more than £50, a charge may be quoted for producing the answer or an answer may be withheld.
There are circumstances where information may be withheld i.e. National Security or commercial confidentiality, but there are (simple) tests to be applied before citing these grounds for refusal.
Different Govt departments suffer from their own cultures as far as FOI is concerned. The Department is not supposed to lie, but the the Police Forces, MoD and BBC have sometimes failed to cover themselves in glory in this area; the BBC and Police spending tax money on fighting legal requests from the Data Commissioner's Office. It's partly understandable, as the the first 2 have to inculcate secrecy into their DNA - I make no further comment on the BBC.
Where the information has already been released or is available elsewhere, a simple reference to this source is all that is required.
FOI offers a great opportunity for military folk to develop non-core skills - in particular the pro-active use of marketing (see the RAF website). A simple link to the DE&S website could have deflected the enquiry about braid. Likewise, considering the presentational aspects of a matter (from the viewpoint of those that may disagree with you or wish to oppose you) and pre-releasing information can be a great time saver.