Unpredictable hobby income & Housing Benefit

Hi everyone. Just looking for any advice anyone would be kind enough to give on my situation.

I've been doing a hobby for a while now, and as of late has brought in some money which I am feeling uneasy about due to claiming Housing Benefit/Council Tax. This hobby is by no means a steady regular income, it is unpredictable and sporadic. Some months I may get some money for something, others nothing at all. I also have not declared myself self-employed, but due to the income it will obviously be classed as 'work' and be treated as such so I think I should declare myself self-employed.

I'm at a loss as where to start.

Any help or advice would be greatly appreciated.

Thank you in advance.