I take my own drinks, I won't spend my fee on the bar prices for a coke or lemonade. (
although some venues don't like anyone bringing in their own drinks), I might have some food if invited but only after the guests have been up, or accept an offer of a coke if they remember, but only if I really do need it. I don't take any food on the basis I've nowhere to sit and eat it, although might take a bag or wine gums, or something similar with me.
Even on the odd event where the venue will give me drinks free, I won't abuse it one or two is the limit.
The job I did Saturday I was at the venue for 5pm, for a 7pm start, and even though there were lulls in the night as the guests arrived, for the buffet but was on my feet, behind the deck the whole time until I finished at midnight. I was at the venue for the best part of 8 hours with no way of getting food or drink unless I take my own.
So I don't think it unreasonable that clients at least offer a little hospitaility. Whilst self employed you can always try to apply .....
http://www.hse.gov.uk/pubns/indg244.pdf
Years ago our t&C always stated access to a dedicated changing room, and a proper break, with food and refreshments had to be provided by the client. I was so hungary Saturday I stopped of at 2am at McDonalds which was on the 25 mile journey home