One of the biggest jumps between GCSE and A Level is the volume of reading that you have to do. Of Mice and Men becomes Jane Eyre; Tess of the D'Urbervilles; Birdsong, or the Handmaid's Tale... etc.
Firstly, know that you are not alone in finding these texts intimidating. They are long and, for the most part, written a long time ago. As a result, their language is different to our own - but not quite as different as you might think.
For example, Wuthering Heights begins: "1801 - I have just returned from a visit to my landlord - the solitary neighbour that I shall be troubled with".
The bigger words are scary when used in the same sentence. One of the best ways to tackle this fear is to imagine a character behind the voice. If you're feeling confident, it can help to read the books aloud and give each character a different tone - see what works for you.
Thirdly, it's okay to read SparkNotes summaries before you tackle the actual book - as long as this isn't where you stop. Read the summary and find which parts of the plot interest you - Wuthering Heights has some great, active female characters; Birdsong is Tragic and heartbreaking in its depiction of the War; and at the very least, being able to talk about a Dickens novel with genuine knowledge will make you look impressive at University interviews.
Whatever you are interested in, A Level texts are chosen for their depth and relevance; if you look hard enough, you can find them interesting and even fun to read. Start with an open mind and you can go a long way.