I started working freelance in Canada in 2025. In 2024 I worked in the UK and made all my income and paid taxes in the UK. Do I need to pay taxes in April 2025 to the CRA

If you are a non-resident of Canada, you would only need to file a tax return if you had Canadian-source income. If you didn't have Canadian income until 2025, then you don't need to file a 2024 tax return.