is it bad to write a creative which has been done plenty of times before? 
i.e. my creative is about a man finding his father (cliche); this has been done before in previous years . 
Does doing such a generic creative concept hinder my possible marks in any way?
Hey! 
It certainly doesn't hinder your marks!
Only if you do it very very generically, superficially and cliched
The way to do it is to take that idea and make it your own. Put your spin onto it. 
As owidjaja said, add your own personal voice to it. 
It's like when a class does a project on the same topic.
They're using the same basic idea/concept but the aim is always to make your rendition of it stand out from the rest.
Because its already been done, that's how you differentiate yourself.
Once you're done, post it in the marking/feedback section to get marked and people can help you to i,improve it in terms of complexity and depth
Good luck!  

For Mod B Hamlet I have been given different advice by different teachers about including reference to an actual production in my essay. I want to mention the Royal Shakespeare Company filmed production to strengthen a point about Hamlet's insanity and one teacher says this is advantageous while the other discourages this. What do you think? 
I've heard the statements about adding quotes and stuff from critics/academics and done well, i've seen they generally enhance an essay. So if you think you could do it well, then go for it!