The second year A-level student will be training with six other hopefuls drawn from a series of talent-spotting tournaments held over the summer and autumn.
Playing for the Welsh Exiles, Mills caught the eye of the coaches whose aim is to expose players to the potential of playing at World Series and European Series level.
Mills will attend his first coached session at the WRU Centre of Excellence in Cardiff on Monday.
“It sort of passed me by to begin with as I had just been to Cardiff to have my university interview there to read medicine,” said Mills.
“Not until the next day did it fully dawn on me what the invitation meant.”