Realistically I never thought they would cancel our holiday over just one day, but I was then advised to check if I could pay on line which I did at 11.45pm last night, so all sorted, stress over.
I had reminders sent after I had missed a payment not before though, (I had canceled but they hadn't done it)Thank you all for your reassurance.
However, a special thank you to Tink. I had booked direct with Disney and having read the terms and conditions it stated that "payment must be made 8 weeks out and that no reminds will be issued and cancel may ensue if monies are not recieved".