Languages always, always, always have a capital letter in English. Writing 'english' or 'french' in lower case is never right. It is always English or French.

For other lessons if you're talking generically you don't have to use a capital e.g. I had a science class today. I have maths tomorrow.

When I write them on my CV I use a capital letter but that is because it is the specific name of the exam that I sat, and therefore it is best to capitalise. The same for the name of a specific degree course or module e.g. I have a degree in Chemistry.

There is no need for capitals letters in that case