Children in Key Stage 2 need to keep up the habit of reading regularly. Your child has been issued with a yellow reading diary which needs to go home each night and brought back into school everyday. Children should read every night and have their reading diary signed by an adult. Children don't just have to read their library book - it can be the newspaper, tv guide, comic etc.
If your child is still getting to grips with de-coding skills (e.g. breaking up words, using letter sounds, making guesses to fit the sense of the sentence etc.) then reading to you will give him/her plenty of practice in this. But don't let it feel like a test. If your child gets stuck then simply say what the problem word is and move on.
As your child becomes fluent he/she will still gain enormously if you continue to read together. Maintain an interest and discuss your child's choice of books. Think together about the plot, the characters, the facts (if it's an information book) and swap thoughts about what you're reading. You can do this with any of the books your child reads - not just his/her 'school reading book'.
Above all enjoy books together. And remember, no primary school child is ever too old to enjoy being read to. Ten to fifteen minutes a night will be truly valuable and will certainly make a difference to your child's progress in school.