Nothing lost in putting in a cheeky offer - they can only say no. If it's still there in a month i'd come back again, offer them £300 less. At the very least i'd want broker discount kind of money (£3500) off this if you really can't stand to join the queue. Come in at £4000 off, stating broker discounts and the fact that it is second hand. They will probably come back at you with the fact that it is available now. Settle on broker discount.
It's in the best colour

- did you want DSG, or just considering it because this demo has it? I personally wouldn't have DSG if it was a free option, if you don't like autos then you might well regret your purchase after a short while. Always make sure the car being offered is what you want, you may be wanting to jump the queue, but you'll probably have to live with the car upwards of 2 years.