Congratulations on passing your NVQ 2
Try to find out a bit more about the potential job coming up in October, and let your manager know you would be interested in it. It sounds promising if they have given you a lot of responsibility already, and also you are familiar with the routines, policies and practices, as well as the children. Maybe discuss the possibilty of starting your level 3 as a volunteer and then applying for the job and taking it from there. Some providers let you start your course when it is convenient to you, not just from September.
I am doing STLS level 3 and for that you need to be in paid employment, but I don't know if it is the same for CCLD level 3.
Best wishes x