I got a B in English Lit and Lang at GCSE, and got an A in English Literature at A-Level, so it is do-able. Personally, I feel like the most important thing is to read as much as you can! Not only do you build up a good bank of wider reading, but the more you read, the easier it becomes. I remember being really intimidated by the texts when we started A-Level but they became easier and more natural to read the more I read outside of class. If you are struggling with the texts, the website 'shmoop' is very good, especially the summaries which might make it a bit clearer for you. Also, reading does really help with your technique in essay writing (I'd also recommend loads of past papers, even making up your own if you run out of them!).