Self-employed expenses in case of no profit

I am currently employed full-time for a company but wish to start a business on the side. Unfortunately, the nature of the business is such that there are unlikely to be profits for the first 1-3 years. Referring to https://www.gov.uk/expenses-if-youre-self-employed : "If you’re self-employed, your business will have various running costs. You can deduct some of these costs to work out your taxable profit as long as they’re allowable expenses." Does this mean that these allowable expenses will simply be fully eaten by me for the first few years before I have profit to deduct from, or can they be deducted from my income from the full-time job?

Hi,
They can only be used against the self employment to generate a loss that can then be used against future profits.
Thank you.