Irregular job - advice please

[snoop12]

I am unemployed and have a tax allowance of £7000. I buy motorbikes for colleagues abroad, they ask if I can find a particular bike, they send me the money and I take a small percentage. I don't use my money. To my surprise I made roughly £6000 last year. I need to declare this money in the next tax year. This is an irregular money maker, for months I can do nothing. Can I just state the amount I have made and describe what I do in the tax self assessment and leave it at that? I have some expenses, petrol and a trailer. Can I add these?
I want to keep things as simple as possible.
Any advice welcome.

[King_Maker]

Business expenses are deductible from the commission income.

You may need to consider Class NI also.

When did this start?

[Peter D]

You should be registered as self employed. Regards Peter