generate random letter number grid

Hi there. I need to create this

in multiple forms; some with letters and numbers, some with random words all english, and some with random words in english and another language.

Please can you advise me on the best [read easiest!] way to do this?

Is there away to make a template that can easily re- generate when want to refresh. 

And how would I set up formatting to specific fonts etc

Thanks so much