The phone line doesn't really help though if you have to fill out a specific form (eg. for bringing >EUR 10000 into the EU) and the checkpoint is unmanned. I've had this issue before at Manchester T3 - the problem was further compounded by the fact that the phone wasn't working. I eventually called Customs at Gatwick from my mobile and made a verbal declaration to them, and then submitted the form when I was down in London a couple days later.