Can I do an integrated PhD with two years of research followed by three years of PhD in UK/Australia?

No, most integrated PhD programs do not follow a structure of two years of research followed by three years of PhD.

Typically, integrated PhD programs combine one year of master's-level coursework or research training with three years of PhD research, totaling four years. This format is common in the UK, Australia, and the USA. A two-year research phase before starting the PhD is not standard in integrated PhD tracks.

If you want a longer research preparation period, you may need to pursue a separate master's program before applying for a PhD, rather than an integrated PhD.