Accruing holiday over maternity - what if you don't return to work?

[Leleophants]

Could you still use up all this holiday before officially resigning or do you lose out on it all if not back for a certain amount of time? Talking about statutory.

You will either take it within the leave or be paid it in bulk on leaving.

If you don't return, you would have to pay back any thay you had taken but hadn't accrued by your due return date.
If you only take what you would have accrued by that point then you wouldn't owe anything.