FTTP install - what ducting can i install in advance for engineer to feed fibre through?

I'm having FTTP installed. I've heard of people installing the ducting so the engineer just has to blow the fibre through, which would help to get the fibre threaded through the building fabric to where I want it, without expecting the engineer to crawl across my unboarded loft and poke it through my trunking. The fibre will be coming from a distribution pole outside my house, about 3m from the current POTS attachment point at gutter level (I have a short POTS drop wire currently, and FTTP is on the same pole).

What ducting product should I buy to do this?
What's the minimum bending radius?
Should I leave about 5m rolled up at the gutter for them to take across to the pole?