Well, to many a fanfiction writer the plot might sound cliche, but I have two things to say about that:
Firstly, it's exactly what a slightly spoiled ready-to-prove-himself crazy Potter teenager might come up with (sometimes my sons come up with all kind of "OMG! Seriously?! What were you thinking?!" ideas so I think it's completely realistic)
Secondly - whatever you think of the story, it's secondary to all the relationships and interpersonal feelings it reveals and it's not really about what happens, but how the lines are delivered (just you wait for Ron and Scorpius Malfoy - adorable and funny!), heart-wrenching Harry's struggles, the on-stage energy between the characters and all that theatre magic (the technical aspects are just off the charts, I want to see it again to at least get an idea how they did some of the stuff!) - and last but not least, a theatre buzzing and full to the brim with excited, exhilarated Potter fans - it's pretty priceless to see and I will go as far as to predict that just leaving the script will leave you disappointed and seeing it live in no way would. It's just touching and wonderful. :)
Waiting for your new chapter, darling - it's so busy here you have to give me a day or two to do it right, but I'm looking forward to it! :)