Hi sleeplessinderbyshire:
First can I direct you to the Pearson learning pages here on Mumsnet:
www.mumsnet.com/learning - this will give you a lot of basic information about curriculum and how things are now taught.
I would also encourage you to look at the prospectus from the school(s) you are interested in sending your DC to next year. At some point in the autumn most schools will have an open day for prospective parents - this is usually also explained in the information your LEA will send you about applying for a school place (you can check your local county council/ city council website for this information - mostly now all on-line). I would strongly advise that you visit schools and have the tour around and listen to what the head, etc... have to say before deciding on which school to attend in your area, if there is a lot of choice.
Now about Teaching Assistants (TAs). During the labour government funding for support staff in schools greatly increased. Usually there are 2 TAs in Key Stage 1 (Reception - Year 1 - Year 2 - ages 4 - 7) and usually 1 TA in Key Stage 2 classes (ages 7 - 11). However, sometimes when a child has special needs, they may also have additional TA support in that class to help deal with that child's needs.
Differentiating work: This is from Teacher's Media and is a video about teaching mixed-ability children in Year 2 (ages 6 - 7): www.teachersmedia.co.uk/videos/mixed-ability-in-year-2
I think this will give you a better idea of what is meant to be going on in terms of teaching children at a number of levels.
What you'll find in practice is that part-way through Class R the children will be placed into groups for reading, writing and maths. They also may have general groups of very mixed ability - for work that can be done together at all abilities (for instance painting). These groups will accommodate those children in reading who can already read quite well, can sound out well and read one-syllable words, can sound out well but need support blending sounds, and struggling to sound out words or read at all. This kind of thing will also apply in math and writing.
What happens is that children who are struggling will probably get more time with the teacher/ TAs to really support learning and improve progress. The teacher will work with all pupils, but more able pupils can be set off with work and left to it, with light supervision and less able pupils may need more help/ guidance. As a parent it is sometimes hard to see the teacher not spending a lot of time with your child - but there are 30 pupils - all with individual needs/ abilities - and so it is important to understand that your child is sharing resources, including the teacher. Where you can help - is to do as much reading at home as you can, support homework policy and where you see your child struggling, try and find ideas, resources, games, etc... to support learning at home. It's a triangle really - child - teacher & parent. We all have a part to play.
HTH