Sounds exactly like DD1, similar sort of GDD diagnosis in MS reception.
Reception year was bearable as mainly play, year 1 was a struggle, year2 was a disaster and the school really had no idea what to do with her, they looked after her well but did nothing for her academically. The gap just grew wider and the school real wasn't one that had any interest in SEN children, statement was meaningless.
So year 3 was in a SS, academic progress has been amazing. Year 3 seems a popular transfer year into SS and all those that started at same time were all in a similar boat as us - came from MS schools that hadn't really included or taught them. First term was challenging as they all had to get used to actually doing some work! So now making good progress. It's hard to say at this stage what the future holds other than there will be a lot of tears and heartbreak as you adJust.
Don't want to paint total doom and gloom, yes there are a lot of negatives, but some advantages.....a 9 year old that hasn't heard of one direction, doesn't even know what ear piercing is, no backchat, doesn't even question how Santa delivers all the toys....the list does go on! You have to be realistic, life will be different, there will be a lot of tough decisions and battles ahead, it will be hard work juggling it all but you will survive it all.
Advice is : fight tooth and nail for the statement, once you have it don't believe a word the school say about what they are doing and ask for evidence, look at other schools in the area MS and SS some are better than others, push to make sure your getting sufficient SALT and OT input (laugh when you realise what they think is adequate) apply for DLA early on - we were clueless about this until SS, the extra money can then be used for private sessions. Best of all....keep coming on here as this is the one place I've learnt the most from x
(oh and delete any friends on FB who put those 'I'm so proud that junior has gone up a book band, won star of the week and has been selected for the 2016 Olympics' smug updates to save your sanity!)