I did an RPL for my visa application, but that was all written documents no interview (and IT not childcare). From what I remember the key seemed to be knowing the criteria they are looking for and writing your experience around it, it wasn't too difficult but completely different to a phone interview I imagine. Also I thought the whole point of RPL was to be able to show what you have learnt from non formal qualifications so I am sure they are very used to answers based on experience alone and you will have learnt far more from your experience than you realize. I suppose the only advice I can offer is try think through some examples of things that you might be asked but also just go with the flow a little am sure you know your stuff so relax and pretend you are explaining it to us on BB!