Lamayuru sits on NH1, the Srinagar-Leh highway, roughly 115 km west of Leh and 105 km east of Kargil. A private jeep from Leh takes about three hours in good conditions, longer if you stop at Alchi, Likir, the Indus-Zanskar confluence, or other sights along the way.
Shared taxis and buses between Leh and Kargil can drop passengers at Lamayuru, but schedules are thin and not designed around sightseeing. For a day trip, hiring a car from Leh is the practical choice. The highway is seasonal in the wider sense: the Srinagar-Leh route depends on passes that can close after heavy snow, especially outside late spring to autumn.