Maths Foundation or HighterWatch
"Thank you in advance for your help'
Because a C is highest attainable grade in foundation, the test paper is easier and therefore grade boundaries are higher. However with higher papers a C is usually 50%. Anyhow you could surprise yourself and come out with a B
Writing practice essays? If you're also doing English externally and you don't have a teacher to help, you could maybe find example essays on the internet so you can see how to structure essays/questions and if you look at some mark schemes you'll be able to see things the exam board want you to include