Hi Filofax:
Agree with TeenandTween - KS1 (Y2) SATs are teacher assessed, may not necessarily be given at a set time (i.e. mid-May - although our school does use same week at KS2 SATs) and tend to be handled gently and informally, as much as possible.
I think you need to step back and think about the purpose of SATs. Taxpayers are funding schools to educate our future generations and this is a means of ensuring that children are making appropriate progress (or to put it bluntly - that teachers are doing their job). So doing more yourself - although wonderful - is in fact helping teachers to look better than they are.
Should schools explain more about SATs - by gosh YES must be the answer to that. Parents hear rumours, get wound up by talk like this on MN, etc... and just a brief meeting or explanation to parents at parent/ teacher meetings or in a newsletter would help clarify a lot.
I do know that for KS2 (so Y6) SATs are more formal (exam marks, not teacher assessment) and many schools here have a meeting explaining what they include, when they will be given and how the school will handle various groups: struggling students (intervention/ extra work), students at expected level (more work than usual perhaps, or stretching them with high targets) and above expected performance students (so preparing them for L6 SATs/ working in small groups/ enrichment activities). Many schools send workbooks for SATs preparation and/or extra work in Y6 - and again parents are often told why the school is doing this and what they'd like parents to do to support this.
Now for Y2 (KS1 SATs) if you are worried about what you can do at home can I introduce you to BBC Bitesize KS1: www.bbc.co.uk/bitesize/ks1/ - this has 3 areas Literacy/ Numeracy/ Science and there are games which you can play for more practice and you have control of difficulty. I have found these a very useful barometer for how my DDs were doing - DD1 struggled ( even on EASY level, she ended up getting NC L1s at KS1 SATs) and DD2 found them a breeze (even on DIFFICULT level, and she ended up getting NC L3 at KS1 SATs).
MN has a bit of information on expected performance/ progress through NC Levels & SATs here: www.mumsnet.com/learning/assessment/national-curriculum-levels - start here and click headings in the 'related pages' blue box (usually on right) to find out more.
HTH