You do NOT treat it as income. If you do you will be taxed on it.
If you are a sole trader then you do not disclose cash injections at all. All you disclose are your income and expenses for running the business.
I would suggest that if you do not know the answer to a simple question as above, you should seriously talk to an accountant. If you have a small business it may only cost a couple of hundred pounds, but trust me, it is worth it.
You obviously don't know what is treated as income, so do you know what is treated as allowable expenses? If you make a mistake it could cost you hundreds of pounds.
Talk to a local accountant and get a fixed fee up front.