Unable to donate due to DOB format anomaly
Have you formatted the date in Administer/Localization/Date Formats? For the UK  'Complete Date' is set to '%B %E, %Y', and 'Complete Date and Time' is set to '%E%f  %B, %Y %l:%M %P'.  Also 'Date Input Fields' is set to 'dd/mm/yyyy' which is probably the critical one in this case.