Sorry for short response, but supposed to be working
We asked for a 2 week extension on EH & got it, but we were in a different situation of not getting offered a place there until a month before the Thomas's assessment. & we managed to delay the whole thing until finding out about Thomas's 1st because my hubby was away with / busy with work & so we couldn't go back to the school & speak to the HM.
We have twins & so there was absolutely no way we could afford the 'lose' the deposit approach! We also spoke about our situation with our Nursery head & she was full of advice & helped us have the confidence to push for an extension (whilst helping us come up with good reasons to put forward without sounding like we were waiting for Thomas's!). We were able to use the boy / girl argument mainly as whilst I 100% wanted the twins split up, I was feeling very emotional about splitting up them into 2 different schools at 4yo! If you have different sex chn maybe you could use this argument too?!
Also worth noting, that because of the sibling, 50/50 & equal spilt birthday approach of Thomas's (& the then mass extradition once state school's have offered their places in April) that whilst apporx only 9 chn from the nursery started with a place at Thomas's in November, by July I think that had gone up to 17! So if you do decide to take a punt (seems hard to do!) on Thomas's, you could well end up with a place by the end of the year, although I do appreciate most people can't have that mentality!
We have only been there a few weeks, but we (all of my family!) LOVE it & the chn are so happy - the head is VERY forward thinking & whilst I doubt there is very much in it in terms of secondary school places offered, it is as equally important to me that my chn enjoy primary school rather than lose their joie de vivre because of stressful prepping & cramming.
Anyway, do PM me if you would prefer a chat about it - I won't get any work done at this rate!!!!