When I first started, Stage Clothes were not allowed, but now this seems to have been relaxed when you need specific clothes that you only wear for work - like a uniform. I also claim for cleaning costs, as they get pretty manky!
When I can eat at home, that's fine, but if I do a show, then if I have a meal after the show - restaurant, or even fast food, I claim it as an expense, because it's impossible for me to wait until I get home. I used to do visiting examiner work too, and I was able to claim back the cost of the hotel, and an evening meal, and I've used the same set of rules in my self-employment, as it's not unreasonable.
I also claim CDs, sheet music, stationary, strings, new cases, flight cases, computers, music software, licenses, MU membership, and as I do lots of the music background work at home, I claim a proportion of my gas and electricity, water and sewerage as working from home expenses. My fuel bill last quarter was £700, so the 50% for electric and 33% for the others seems fair, as my job costs money.
At some times in the year I go away for a month or two at a time - my digs are claimed, plus any expenses living away from home costs, over and above what staying at home would cost. My accountant disallows some things I give her, but when I can justify them, she puts them through. In one of my away jobs, I'm the production manager - and buying coffees is expected - even though the production company does not reimburse me for this. It just comes with the job, so thirty quid for food for other people is a legitimate expense of doing my job.
Porterage is also an understood item by the revenue. So if you are a drummer, or percussionist the extra cost of moving your kit around is also legitimate. So hiring a van if your car isn't suitable is also OK.
One area where you need to be careful are when deps are involved. As I understand it, paying a dep can be considered an expense, rather than them invoicing you and you paying them yourself. It doesn't make much difference.
One thing that may catch people out are when they work in the same place for an extended period. 4 days is being bandied about as the limit - and going over this makes the gig your place of permanent employment, meaning that even though you retain your tax status as self-employed, you may have to pay class 1 National insurance on top of your Class 2 and 4. This is because the rules were changed (and being talked about being changed back again). So if you get a job, say playing in a pit for a show, you might find some on the ball clients will deduct NI at about 10%. With pit work, the dep you need to use will want the usual rate, but you are not getting it, because of the NI deduction, leaving you out of pocket.
It's getting more and more complicated.
On the receipt front, my accountant tells me to keep every single receipt, and then it is easy to show that you have not claimed them all, but just an acceptable and reasonable number.