The formal style of storytelling is one of the features of an English essay that distinguishes it from essays on a free topic. The British are serious about the style of expressing thoughts in an essay, therefore it is not recommended to use abbreviations and, generally, allow frivolity in the text. Also, any essay, regardless of topic, has a certain structure. But first things first.
Traditionally, the essay has a fairly formalized structure: introduction, main part, conclusion.
Typically, an examination essay should be 180-400 words in length, but this framework is not rigid and must be indicated in the assignment along with the topic.
Before writing, it is worth remembering that an essay is not a detailed essay-discussion on a free topic, but only a clear and capacious expression of thoughts on a given problem.