What is the role of contemplation in the life of a layperson?
It is both interior and active.
What do I mean?
There is a point in St Bonaventure's Itinerarium that describes this contemplative life. And I think it applies comfortably to the lives of we laity, praying and living in the world, so to speak.
St Bonaventure discusses a moment when he was praying at the spot where St Francis of Assisi received the stigmata. St Bonaventure saw the significance of this event in the light of humanity, of the world, of the history of the Church. At this spot, at the point of receiving the stigmata, says St Bonaventure, "...Saint Francis passed over into God ( in Deum transit) in the ecstasy (excessus) of contemplation and thus he was set up as an example of perfect contemplation just as he had previously been an example of perfection in the active life in order that God, through him, might draw all truly spiritual men to this kind of passing over ( transitus) and ecstasy, less by word than by example." (Itinerarium)
This is what Thomas Merton calls the "only one vocation".
Wherein we are called to an interior life, to prayer, to prayerand work, to a relationship with our Creator. And then to share, pass on, the fruits of contemplation, His Love, to others. Be they our children, our family, our spouses, our friends, fellow parishioners, our work colleagues, our neighbours.
We may do this imperfectly. God knows I do.
We are called, in the words of Merton, " to become fused into one spirit with Christ in the furnace of contemplation and then go forth and cast upon the earth that same fire which Christ wills to see enkindled." ( The Seven Storey Mountain)