Welcome Home, Gemma! Thanks so much for stopping by planDisney with your question from across the pond. It's always a treat when I get to help a fellow 
Disney Vacation Club Member--now let's make some magic!
One of the many great features of Disney Vacation Club membership is the flexibility to use your 
Vacation Points for all sorts of adventures, from 
DVC resorts with the comforts of home to voyages on 
Disney Cruise Line to 
international villas and resorts. Our Home Resort is 
Disney's Polynesian Villas & Bungalows which our family adores. However, we also enjoy trying out new DVC resorts--so I've been logged in on the computer on more than one occasion to snag a 7-month booking on the date that my window opened!
Gemma, your 7-month booking can be made exactly 7 months from the date of your planned arrival. So, for your September 15 vacation, you can make your 
reservation on 
February 15 at 8:00 AM, Eastern Standard Time. I recommend having some alternate dates and locations in mind in the event that your preferred resort is not available.
Don't forget that you can have up to two active 
Waitlist requests per Membership, per Use Year. For instance, if you have your heart set on staying at 
Disney's Riviera Resort but find out that it's not available for your September dates, you can book at a different resort and then create a Waitlist for Riviera that will expire either 31 or 7 days before your check-in date (your choice). I can't guarantee that a Waitlist will come through, but Members' plans change all the time so it may just be your lucky day!
Gemma, I hope that the stars align for you to have the most jolly holiday this fall! Thank you again for visiting planDisney--If I can help with any other vacation planning questions, please don't hesitate to 
reach out to me directly. 
Stay Magical!
Susan