I was in same boat last year.
we did in year transfer.
felt bad as same sort case as you school 1 dong badly others were leaving.
we had been there since preschool
Se needed additional support and found transition r to 1 hard and 1 to 2 was disaster so after 1 term she moved.
Head only found out once i had filled in year admission form
sent to la.
They then made offer which I accepted then la woman cheerfully said oh we emailed new school and old one.
I had not even had chance to talk to head, did not want him to find out like that as liked the man
Arranged appointment where he blew me off got dumped with deputy head who had no idea who i was who my child was or what it was about.
I told her and her reaction was if you want to leave leave.
New school smaller , much more interventions, more activity
It was scary but she settled amazingly quickly nearly been a year but was such difficult time.
At this point just veiw a few schools
they will tell you if they have places or not
I had only 1 school in mind. Emailed them, email back they had vacancies 3.
We looked around. decided to apply rang la and was only 1 vacancy as 2 were reserved so acted quickly and so relived got a place.
I gave notice on last day term at 3 pm handed letter into reception.
3,10 picked up dd and asked teacher if could have a word.
Told her dd would not be back next term.
god she went mental , defensive was relived to walk out school gates and never go back.
But what made it awquard and same with you.
you have elder child at same old school.
I had 2 younger ones at preschool next door.
lots parents seemed bit miffed by fact i had left.
They kept coming up to me for entire year saying its getting better and defending the school or telling me who left. since moved younger 2 this year so clean break.
but another woman who left moved eldest 1st, got r child in and reception starter which gave sibling link to finally get her year 2 child moved.
new school would give youngest a sibling link.
much easier move 1 or 2 now than all 3.