If you sell to consumers, the Competition and Markets Authority (CMA) has guidance on price transparency under the Digital Markets, Competition and Consumers Act 2024. It says mandatory charges, which include taxes such as VAT, admin fees and unavoidable extra charges, belong in the total price. Presenting a charge separately doesn't make it optional if the customer has to pay it.
The guidance also recognises that some work is bespoke and can't be priced in advance. In that case, a business can publish a price list, show a realistic 'from' price, ask for the customer's details first, or wait until it has assessed the job before giving a firm price. The CMA gives home improvement, removals and cleaning as examples of services that often quote this way.
If you're VAT registered, the standard rate is 20%, so a price excluding VAT is multiplied by 1.2 to get the VAT-inclusive price. Ask the AI to show both figures if you quote to business customers too, and check the sums yourself. This is general information, not legal advice, so check the CMA guidance or take advice if you're unsure how it applies to you.