To put it simply, I would put money on you not being able to write a statement to the level required. Why? Because writing statements is much more complicated and technical than you think it is. It's not just like writing a story.
As
@FBi7 alludes to, there is a format for writing statments called the 5 point plan. Part of this format is writing summaries of the evidential value at the top of the statement, with another section being dedicated to the people mentioned in the chronological account and their involvement in the incident. This is important as CPS lawyers who have very limited time to prosecute a volume crime case won't necessarily read everything in the case file. They'll look at the incident summary on an MG05C and try and link up key pieces of evidence in the statements. They use the format of the statement to easily work out what is relevant and what isn't depending on what the defence may bring up.
On top of the format, there is a lot of technicality in how an incident is described. Everyone should have a full 10 point description at the end of the statement so help link up who is who on other statements and CCTV. Most people haven't even heard of a 10 point description, let alone know what all 10 points are.
It was also mentioned about ADVOKATE. This is a mnemonic around some case law which is really important for witness statements. It includes things like describing the lighting and any obstructions in your view of someone or an incident. How long did you see that person for? Was it a split second or longer? When they hit someone, how many times did they do it? Where did they hit them? What with? A fist? Closed? Left or right hand? What was the level of injury? Common Assault, ABH or GBH level? What defences may be suggested? Do you think it could have been self defence? What made you think that?
Put simply, it takes Police Officers a lot of training, lots of practice and a long time to write good evidential statements that can be successfully used in a prosecution.
But hey, you think you can do it, so it must be easy right?
On the point of you thinking it may not reflect what you want it to say, ultimately you have a choice to sign it or not. The officer will write it and you can change it if something is inaccurate or gives the wrong impression. If it's not signed, it's not a whole lot of use.