Over the past three years I've done slightly over a hundred Official Information Act requests. As a result, I've learned all sorts of things about the process, but one important thing I've learned is that despite the legal power to levy charges for processing requests, government departments almost never do. Of those hundred-plus requests, I think I've only been asked to pay three times, and I've only had to actually send a cheque once (for a fairly substantial request, which required people to delve into physical archives of 1990's cabinet papers. Possibly they had to buy a clockwork emergency mouse for the purpose). The core public service may sometimes be slack and obstructive, and may sometimes be a little free with the deletions and refusals, but at least they accept that the public have a right to know, and generally work to help us exercise it rather than errecting barriers.
The story is different with local government. I've made far fewer requests under the Local Government Official Information and Meetings Act 1987, but in around half of them the first response has been an aggressive demand for payment, which is always in excess of the charging guidelines set by the Ministry of Justice and contrary to the Ombudsmen's guideline [PDF] that agencies should work out what they will release, then how much (and whether) they will charge for it.
I'm not sure whether this is because local government staff are not properly trained in handling requests (how many people use the LGOI&M Act anyway?), or whether it is because the culture of openness in central government hasn't percolated down to them yet.