Usually I faf around with dates, extracting the day value, month value, concatenate etc.
The once it's in a nice format, it usually sticks as text instead of changing nicely to a date field (right aligned etc) Strangely it changes correctly when you click on a cell, then hit return.
Thats ok for a few cells, but not an entire SPL fixture list

Found this tip. Select the column of values (take your concatenated date string and paste as a value)

Data menu>Text to columns>Next>Next>Column Data Format>Date>DMY and Finish
Bang - column formatted.