Hi! First of all, well done on your predicted grades! That's amazing for 12 GCSEs.
For Biology, I recommend the Amoeba Sisters.It's a YouTube channel that does animated educational biology videos. It might look like it's for kids at first, but it really helps you remember stuff! Just having a visual for each topic makes it much easier.
For Geography, try Seneca Learning. Most of it's free. They also do other subjects, but I found them particularly useful for Geography.
Science with Hazel is another great YouTube channel. Hazel does Chemistry, Biology, Physics and I think some maths too. She talks quite fast, especially if you're trying to take notes, but you can adjust the playback speed of the video on settings. She also does revision notes on her website.
Hope that helps and best of luck with everything!