Hi frankie1978
Here's a website that explains different book bands from publishers: www.readingchest.co.uk/book-bands
Schools are getting wise to the fact that parents (& children) are aware of the official book bands - so are starting to do their own things.
That being the case - you are entitled to understand how your DS is doing in relation to SAT levels. So you can ask his teacher at parent/ teacher meeting what she rates him for his Year on the KS1 (Years 1 & 2) or KS2 (Years 3-6) SAT scale as appropriate.
In general - what you need to find out is whether your DS is below, at or above expected level for that year in school.
I think there is sense in both what Indigo & redsky just posted.
If the issue is decoding more complicated words - than yes, that still needs support and encouragement.
Exploring different genre's of writing & as much range of both fiction and non-fiction as possible does help broaden horizons. This is my bug a bear - but schools really miss a trick by not sending home reading linked to history or science topics. Endless weeks of Kipper & Chip gets old quickly.
Indigo is correct as well - in that if your child is doing well he may end up in a pool of students benignly neglected whilst teachers/ TAs prioritise pupils who are struggling. This isn't to say that teachers are wrong - but just to point out that they're obliged to try and get everyone to the appropriate reading level at Y2 and Y6 - so as that SATs year approaches the emphasis could be on raising achievement in the lower groups, who are struggling to master all skills. So back to Indigo - she's right to say that what really helps at this critical stage is to start encouraging as much independent reading as possible. Part of this is avoiding that tick box mentality - child can read, job done then. They need to be encouraged to keep reading. Especially as there is a tendency with boys to see being good at school work as deeply uncool unfortunately.
So if your DS is into series keep going back to the library to get the next one. Also if there is a topic that fires his imagination - try non-fiction on that topic.
The Book Trust Bookfinder is a very useful website for getting ideas on what is out there: www.booktrust.org.uk/books-and-reading/children/
The Guardian had a lovely insert about building a library of great books for children: www.guardian.co.uk/books/series/building-a-children-s-library
There's also a great reading list mixing old fashioned and modern class reading for children: www.kidsreads.com/lists/classic-lists.asp
Hope that helps.