Here's one for you that I only found out about whilst having my pay cocked up. You remember the good old days when they could only take money back off you at a rate of 4 days' gross at a time? Well, if you're not already aware, that's all changed.
You can now have up to 50% of your gross monthly pay (minus Income tax, NI Maternity Pay, Statutory Adoption Pay and Statutory Maternity Pay) taken off you in one lump. See a a little beauty of a publication called JSP 754 Ch2 Sec 4 for more details.
A nice chap in the JPA "back offices" (Ian Sneddon) told me that when I asked how come large wodges of my pay could go missing for no apparent reason. So if you get a mistake in your favour (or even just some act of wrongness) applied to your pay account, unfeasibly large deductions can now be made all at once.
Just thought I'd let you all know in case you weren't aware...