As our couriers operate on working days (with a few areas covered over weekends), bank holidays are not considered to be a working day.
Delivery times are adjusted automatically on the website to account for upcoming bank holidays, especially for Next Day deliveries.
Next Day delivery orders which are ordered on a Friday before the cut-off time will be scheduled for delivery on the following Tuesday (with a few postcodes receiving theirs on a Saturday albeit not guaranteed).
If an order is placed on Friday after the cut-off time, then the order will be picked and packed on Tuesday for expected delivery on Wednesday.
Here's a link to the UK Government website which lists all Banks holidays for the UK:
https://www.gov.uk/bank-holidays