I need help editing my soliloquy of Macbeth in a Modern context (gang theme) to a High standard....I am having quite some difficulty with my Year...

If I understand the assignment correctly, you are writing
your own soliloquy based upon paraphrasing of Macbeth's soliloquy.  If this is correct,
then you must focus as much (if not more) on creating the character voice of your gang
leader as on editing, proofreading, or being professional.  A simply paraphrase ( a
rewriting of the soliloquy using words that you understand more easily) is one thing,
but writing a speech for a character to say involves making sure that you have that
character's tone and voice.

I like these phrases that you
have, and think they send your soliloquy in a good
direction:

But
what if it came back to haunt me? What if my brother’s and friends found out?  Then who
would be on the firing line? Where would I go? Surely this isn’t worth it.  I’d be
living in fear day-after-day and there’d be nothing worth living for.  These men are
smart – they’d find and kill me, like I’ve seen them hunt down other criminals and gang
lords. They would be uncontrollable on their desperate hunt and they’d be all over me
not forgetting the cops.

The
thing that your soliloquy needs, to give it the flavor of a drug-dealing gang member,
is, actually, less grammatical correctness and more of a sense of street language.  You
should look at a movie or TV show that you know that involves characters like the one
you are creating.  Notice their speech patterns and try to create a pattern of speech
for this character that really catches the flavor of the
street.

In case you're interested, here's the trailer for a
film version of Macbeth, set in a modern gang world.  The text is
still 100% Shakespeare, but at least you'll get a feel for the atmosphere.  If the link
below doesn't work, the director of the film is Geoffrey Wright, and you can search for
the film using his name.