My 5 nearly 6yr old daughter has a fear of public toilets.
When ever we go out and my daughter needs to go to the toilet, she checks to see if there is any holes in the pan or if the seat is different, she always looks right down the toilet and often she won't go saying she doesn't like it and she wants to go home, even if we are at the pictures or shopping. It affects all our days out. I do take a potty to save the problems but realise I can not do this forever. Please if you can give me any advise I would really appreciate it.

Children go through all sorts of fears at different ages, to her maybe those toilets look like she could fall into them and be flushed down.. sounds silly but imaginations to children are quite real to them.
Reassure her that she will not fall in or be flushed down. The sounds of the flushing in public places can be quite loud and do scare some children.
Also do sit down with her and ask exactly what it is that scares her about them.. chances are that is what frightens her the rapid flush sound as well as how big the seat itself is for someone small.This way at least you know what you aree dealing with and a solution can be found.
Also soon she will probley outgrow this stage

I'm 27 and I'm still afraid of falling in those HUGE toilets! They are also quite cold, take a hand towel or get some of those seat cover dealies. That was my problem (and still is) with public bathrooms. Has she seen Mommy sit on one? Are they the automatic flushing ones? Sometimes those sensors don't pick up on a little person sitting there. It is disconcerting for the toilet to flush while you are still seated for anyone of any age.