gbotley,
Last year I heard of people hearing anywhere from just over 2 weeks before to about a week before, so it could be quite short notice. Be prepared to book a last minute room at the Premier Inn on Manor Royal which is very good value, has car parking facilities and is less than 5 minutes walk to The Base!
Is it confirmed whether or not it'll just be the 3v1 interview or are they doing group assessments as well?