(you can use your years of work in Australia to count towards a British aged pension). Working in Australia does not count towards UK aged pension. It is dependent on how many years of contribution was made into the National Insurance Scheme.
Current Optus Sim only plan for $40 pm is Unlimited calls/Text in Oz and Unlimited Text/MMS to certain Countries, 300 International Minutes to certain countries and 15GB Data. This on a 12 month plan.