@iPoker - Like ClubMan above, I would encourage you to consider getting professional help. The cost is allowable against tax.
Allowances (mileage, lodging, travel, subsistence, etc.) may be payable to you at Civil Service rates before tax, but you need to get approval from the Revenue before paying them out, otherwise they may be treated as taxable income.
Gather and organise all the documentation you can first (invoices, bank statements, cheque books, receipts, etc, then look for advisers in your area and get prices.