Trading Allowance and Travel

m00036

I am an umpire and normally earn just over the trading allowance each year in receipts, although this is the first year I am also employed (so I will be paying tax per self assessment). My questions are:

• If I earn more than the travel expenses incurred, I think I am right in saying that the full amount (including expenses) is taxable as I am using the trading allowance
• If I earn the same or less than the travel expenses incurred (therefore effectively working on a voluntary basis), it still looks like it is taxable (leaving me ultimately at a loss after tax) as it doesn't really fit neatly into any volunteer definition. Equally, how do you distinguish between counting this as 'income' and just someone 'paying someone back'?
• If I umpire for a club or county that is a registered charity, I think I've seen that expenses are tax-deductible irrespective of whether the trading allowance is used but not sure if anyone can help guide me to something definitive.

If anyone has any answers to any of the above, it would be very helpful