Some outdoor pools that are currently open are: Ku-ring-gai Fitness & Aquatic (West Pymble) & Hornsby Aquatic & Leisure Centre. Links: Hornsby Aquatic & Leisure Centre & Ku-ring-gai Fitness & Aquatic
A useful link: WPNSW has given a guide to swim training sets which will help in your fitness. https://www.waterpolonsw.org.au/news/waterpolonswswimtrainingsets/