English Gcse Watch
That said.... if studying both is stressing you out, but you do want to take both exams, I would focus mainly on literature. That basically means learning your set texts and learning how to analyse. In English language, the exam involves mostly the same skills (analysing) and you write your response in a similar way to the way you would write literature responses for the big mark questions. Some say you can't even revise for English language, you can only learn the structure of the exam and how to best structure your response and learn what the mark scheme is looking for. The biggest difference I reckon is just that you have to do creative writing in English language, but don't in literature. Other than that, language is basically a more 'unseen' version of literature!
Over the about 1 and a half years (year 10 and 11) we had of english lessons, my school spent about 90% of all lessons (if not more) studying literature and 10% on language, and even then, all we could do for language was learn the structure of the exam and do practise papers. So basically my advice is if you want to continue doing both, focus on literature if you can (unless your school literally doesn't let you).