Where do you draw the line?

I'm away for work this week and I'm worried I might become embroiled in an MP's expenses style scandal if I claim for too many 13 euro breakfasts. I've not been keeping receipts for the evening meals thus far as I feel bad about the aforementioned breakfasts. Claiming for public transport is OK even though the distance to work is easily walkable right?

Boring thread but let's see where it goes...