This is apparently a variety of Pittosporum tenuifolium - basic details for tenuifolium varieties are eventual height of around 33 feet, but it takes a while to get there.
Planting advice with Pittosporums generally is to plant in Spring - they can be a slightly tender when they're young, so unless you're planting in a very sheltered spot, out of cold winds, best to keep outside (not in a greenhouse or inside) in a warm, sheltered spot, against a wall, preferably south facing, out of winds, over winter and plant in spring.
Can be clipped or pruned in around May or early June - best done little and often (i.e., yearly at that time) rather than waiting till its too big and hacking back hard.

Cheers Bamboo, I think it might be more commonly known has "‘Margaret Turnbull"

Thank you.

Not according to the sites I looked at, seemed to be a separate variety, though its not one I've heard of before.