Pyjamas for school? Why ever not?!

OK, so here's a question for you. How do I explain to my autistic 3 (nearly 4!) year old girl the following:

That because somebody at the school thinks it's a good, fun idea to wear pyjamas for a day to raise money, yes she can actually go to school in her pyjamas not her school uniform for once. But no, she can't repeat this event any other time, because although it is allowed on Friday the 8th, it isn't allowed any other day. Where's the logic in that to someone who doesn't understand conforming and is trying to learn social skills which come automatically to others?

The start of every day is still difficult for me - it's always hit and miss as to whether Sasha will be happy to wear clothes or not. Well actually not happy with, just OK with. She doesn't like the uniform but bears it, and it all gets taken off the second we get home, every day - not just when it's warm like today! She has often asked to wear her nightie to school before now, and of course I've had to say 'no, because you must wear a uniform for school'. So now I'm about to do an about turn - for one day only. She's actually only been wearing a nappy in bed for the last week - don't think they'd want me to send her in just that, although it wouldn't bother her! So I've had to buy some new Peppa Pig pyjamas especially for the occasion to a) entice her and b) keep separate from 'normal' bedtime clothes... Except when I did, the weather was cold and wet. Now it really is warm enough to go in nothing and she'll be way too hot in the new PJs!

There's no point in me trying to keep her off for tne day, as older sister is of course absolutely delighted with this crazy idea and can't wait to show off her HK pyjamas to her classmates - and why not?! For every NT child, its just a bit of fun. For Sasha it's just confusing. For me it will be an ongoing nightmare for some while to come. And so yes I groan, but will have to grin and bear it and make the best of a bad situation.

I'm already apprehensive now that the lovely warm weather has arrived, as eldest daughter just can't wait to be allowed to start wearing her school summer dress. With that comes another headache for me, as youngest daughter would love to be in a lightweight, non-fitted summer dress. But no. School uniform rules say nursery children must wear a White t-shirt and ridiculous elasticated red shorts which are of the one-size-fits-all variety, and yet are already too tight on the waistband for Sasha's liking. Health and safety apparently, in case a floaty dress gets caught on the ever-so-small climbing frame they make use of for 5 minutes a day... Sometimes. Grrrr. Think I need to start a mass mutiny. Except I love the school they're at really! Just wish somebody could make my life a little bit easier!

Am v tired at the mo so I've not written well and not sure any of this will make sense to anybody else... But wanted to say I'm not usually such a killjoy, I promise!