Hello Kaykay
In my personal statement I talked about how I heard of Montessori education while I was volunteering with an NGO in Guatemala and other experiences with children, and how that made me realise that I wanted to teach children. Explain why you think the Montessori method is the most suitable or why do you particulary agree with it and like it. What qualities do you have that are transferable to the course? I would also recommend mentioning your future plans. Still want to work with children? In the country? abroad? what do you plan on doing after you get your diploma? want to pursue any further education? etc.
Apparently you are applying for a different institution. I will be studying this course at the London Institute
https://www.mariamontessori.org/training/what-we-offer/ami-diploma-course/3-6-years/I have not heard of the organisation you are applying for. However, the only official Montessori training organisation in the UK is the Maria Montessori Institute in London. There are other training centres (like the one you are applying for) that are not AMI (Association Montessori Internationale) certified. If you want to make sure of the credibility of your course I would phone the Institute in London and ask them yourself, because they have a list of every AMI certified training centre and like I said, there is only one in the UK.
Also, I remember reading that the reason why the official training centres do not offer long distance training anymore is because they are not highly regarded, unlike presencial courses. If there are any chances you could do presencial instead, I would really recommend it!
Regarding the deadline... I wouldn't waste a minute. Send the application ASAP because it's already May. When I email the Maria Montessori Institute (MMI) I usually get a reply within minutes or a couple hours, so I don't know why the training centre you've applied for is taking so long. Have you tried ringing them instead?
If you have any quesions just ask!
EDIT
The reason why I am telling you about the AMI certified training centres is for the following reason. Maria Montessori never trademarked/copyrighted the word Montessori. That means that anyone can add 'Montessori' in their school name or training centre... but is it really? that's why there are so many Montessori schools around the world that claim to be Montessori but aren't or just adhere to half her teachings. That's why I would make sure you are studying at an AMI certified training centre, because that is official and recognised by the official Montessori body internationally. That also means that proper Montessori schools (AMI schools) would prefer teachers who have trained at an AMI certified centre as well.
I am copy-pasting a couple of links that I think you could be interested in and/or be usefu to you.
https://www.mariamontessori.org/about-us/what-is-ami/http://ami-global.org/ Wow this is very long now!
I hope it was useful.