I’ve decided to start a series of FAQs. Teachers often set the same type of questions for Creative Writing coursework and controlled assessment, so some of you might find this useful:

“I have got a controlled assessment on creative writing. I am dong the AQA GCSE and the Controlled assessment Question is:  Write about an important time in your life? 
I’m writing about moving to a different country in a Aeroplane. I am having a problem with my essay. It’s too short and has to be 600 words minimum. Can you kindly please give me some advice on how to expand my writing? I am looking for Grade B at least. Thank you!”

Firstly, it’s really hard to make a plane journey interesting. Then, if you include before and after the journey, you’ll probably feel like you need to rush through it too quickly. The best method is to choose moments to focus on and mix that with flashback, so you can go into more sensory detail.

For example:
Mood words are highlighted
The sky was a hard diamond blue. Glass and concrete boxed us in, the fine runway strip stretched out so tight it felt like it could snap at any moment. [flashback >>] I’d seen this moment in my dreams. Then, it was hazy like cloud castles that melt to nothing if you look too long. [flashforward >>] This was hard, sharp, real. I felt sick with excitement, sick with terror. The clean, fake air inside the cabin was cleaner than the dirty air I left behind, but hard to breathe.
[flashback >>]
I remember the defeat in my grandmother’s face as I kissed her for the last time, her hands like paper on my shoulder. She held me as if she would never let go and I felt guilty because it was all I wanted and sometimes I think I may never come back.

This is the new version that the student wrote with some corrections in [brackets].

As i[I] walked through the transparent [unclear] building, I saw a metal beast standing at the front ready to take me to England. It was shinning like a polished silver plate. At first, I was scared to get on it but, I could not stop it myself. It’s[It] was shinning[shining] more as the sun was shining. It dragged me through the steps and made me sit on my seat . After few minutes its engine roar[ed] like a monster, showing off its power,[.] m[M]y ear was exploding. I tried not to scream and I could smell the thick cloud of aeroplane fuel around me[unrealistic]. I could barley hold it any more[.] I closed my nose with a handkerchief.

As it started to run on the runway, it pushed off, spraying smoke and painting a beautiful picture to the world[makes no sense]. I tried to hold on tight as it drilled through the air dancing with the wind [cutting through?] and waving bye to the passing air and ground. Finally[,] i[I] was up in the sky like a bird. I was scared when i[I] looked out of the window[.] e[E]verything just looked minor [tiny][,] however it also seem[ed] like I was the king of [the] world ruling the earth from above. I could see the white cotton bed[wool] clouds passing. I could still hear the engine blaring like a monster. While I was carried away, I thought about my new home in England. I was really existed[excited] and emotional about moving to England and started to think about different people. It was nearly lunchtime[.] t[T]he sun was really bright[.] i[I]t burnt my eyes. It felt like the plane was getting melting like ice cubes. I could see the bright blue Arabian Sea from [a] distance it was [, the] most beautiful scene you [would] never want to miss. 
Hi, what you’ve written has too many metaphors/similes. You need to describe the actual details using more plain language to give a clear picture, e.g. the brilliant blue sky spread overhead, and you should link it to reasons why you’re going, how your family feels, and why you are going to England. Adding this in would also help you to increase the wordcount.
There’s also an issue with punctuation and some phrasing which I’ve corrected above. A plane would not fill with smoke or ‘dance’ in the air unless something was seriously wrong with it!