I've had the tax office call me twice in the last 20 years to query deductions I had claimed.
I found them very helpful on both occasions. They told me if you have receipts and you think it's a legitimate expense then claim it. If there is a problem they will ask you for more details and then they will decide to let it go or not. They really aren't out to prosecute Joe average for claiming a PA 31 rating.
What they are after are people who repeatedly make claims for largish sums without receipts or reasons for making the expenditure in the first place.