Muttley:
Look I've been on the other side of this coin - I could write a novel - I have in the past.
Our term for DD1's primary was St. Mediocre - it was a happy, friendly environment but the emphasis was on letting children be children, and getting everyone to a high ability level based on work done in class/ homework was definitely not a priority. Indeed for most of KS2 no homework came home at all once Gove dropped the Labour staturtory hoemwork requirement - the school cited the EEF study which showed homework has little value (lots of posts on homework here on MN - but the person behind the study that showed homework is of only marginal benfit (~ 1 month) in primary even says it depends on the quality of hoemwork and schools should consider parents in this: www.bbc.co.uk/programmes/b04dmxwl
DD1 is now in Y7 - I spent most of Y4 - Y6 doing lots of work at home to fill huge chasms in the curriculum covered by her school, especially in maths. The nett result is she has made a bumpy but reasonable adjustment to her local state secondary school. Friends from St Mediocre priamry school who didn't do this additional work are really struggling and the glaringly obvious thing to me as a parent is all the kids from the feeder school with the rigorous academic reputation aren't freaked out by homework or the concept of revising for exams, don't panic when they're given a project to research and prepare over a fortnight and have all those research/ planning/ organisation skills. Parents of St. Mediocre kids at our new senior school and I have had to spend a lot of time in the first term teaching our kids at home. (And yes it feels jolly good having had a bit of 'you're awful about St. Mediocre' from some friends from the school - to get 'Now, I see what you were on about!' All of us feel that happy though St. Mediocre was, a bit more academic rigour - maybe some regular homework in Y5/ Y6 - would have gone a long way to helping prepare our DCs for secondary.
So my advice is this. Year R will be a gentle settling in to your DC's new school. Don't start your DC's school-life off on a negative note. Yes - keep a watchful eye - but don't arrive day one asking to leave without having even given the place a try - and because you have no idea how long you may have to wait for a transfer anyway, so you need to work with these people. You may just find that your gut instinct - choosing the Academically demanding School over the relatively relaxed one was right.
St. Mediocre presented this 'myth' - they just magically learn here in our gentle, nurturing and supportive environment when the reality was 50%+ parents hired tutors from Year 4 (we're in a 11+ state grammar area) and that's why their results at KS2 SATs looked so good - because the poor kids spend most of KS2 working at home (sometimes quite hard) to make up lost ground. (Oh and the remaining 50% - they were taught separately in Y6, hot-housed to a curriculum of only English/ Maths from December - May - they all did scrape a 4 - but they all ended up absolutely hating school and the ones in that regime have spectacularly fallen to pieces in Y7 at DD1's senior school at least).
Having been there and done that I personally would have preferrred not going part-time at work to home school DD1 who scored NC L1 on English & Maths end of KS1 - and started Year 3 barely able to read and unable to take even 1 from 10. I put in 4 years, working incredibly hard, to turn that around. But if I could have chosen an academically rigorous school, a school sending home regular, well-planned and purposeful homework assignments, knowing what I know now .... gosh, no brainer. And indeed, that's why when we moved DD2 changed schools.