I parked on double yellow lines that were quite faded and got a ticket. I argued that i couldnt see them when i parked (although to be honest they werent THAT faded and i was trying it on really!)
ANywya, they let me and said they would re-paint the lines, which they did within a week!
I don't think its an appeal. If you got a fixed penalty ticket, you are entitled to have it heard. They issue a Fixed Penalty Notice and they will take no action against you for 21 days to give you the chance to pay up for your misdemeanour without going to trial. If, however, you don't pay, they can take action against you and you have the chance to defend yourself. You do not have to admit you were at fault just because someone has given you a ticket. Go for it.
just to answer the qustion yes the line must have t bars at each end and no broken lines but this doesn't mean you should park there (morally) as it's probabley a danger to you and others and that is why there is a yellow line