its not really that difficult yo get back on the nmc register. If you can prove you have done some nursing experience (which you will be doing in oz) then there shouldnt be a problem. i let my registartion laps twice for maternity leave, i know a bit different, but i still let it lapse twice and not a problem either times to re register. It does seem silly to have 2 registers going. Im going to let mine lapse here again when we move over to QLD.
good luck