As a bankrupt, can I retrieve bank statements from over 20yrs ago. I wish to prove to my estranged (now grown up kids) that I was supporting them through their time living with their mother from whom I was divorced.

Highly unlikely as most banks destroy such records after about 6 years.
You could ask, after all you never know what they'll say..

Thanks for that response, I did think this was the case but obviously needed some advice from others rather than go direct to the bank. Regards.