Sorry for the delay in replying. It was a busy week at work and I didn't have time to even look to see if anyone had replied.

It looks at though Lycamobile will be my only option if I want to go with a UK eSIM. My Australian provider suggested having the local carrier as eSIM as swapping Australian eSIM accounts whilst in UK could work, but could be problematic as well.

Thank you all for taking the time to reply.