Leeks

I've grown leeks both ways B&B and didn't seem like any difference. The trick (as far as I am aware) is to make sure that you dib them in deep as this is the bit that stays white and then they can be earthed up to make the white bit even longer. I guess that is what a trench does in that it will be filled in over time.
I wish I had space for the leeks........ With the slow start this year my allocated space for the leeks still has stuff in.

I was going to put the leeks where the broad beans are as I haven't got potatoes in the plot this year. I've opted for growing some in planters started off in the greenhouse.
Is it ok to follow beans with leeks?

Mine went in last week so you are fine putting them out now.  You can still get white shafts by either earthing them up as they grow, or covering the shaft with something like a toilet roll inner, you just need to exclude light.  The inners will look very big over them at the moment but the shaft will grow to fill them in time.