In my opinion, Biology A-level can be somehow challenging due to its significant depths in terms of content and concepts. Since you pursued combined science Edexcel, it might even be more challenging although manageable with a person's unique dedication. To prepare well, you need to review core biology topics and use resources such as Khan Academy, BBC Bitesize, and textbooks for more support.
Also, consider practicing with past papers. In case you need help in this regard, dont hesitate reaching out to me via DM
Good luck!