How close is it to the house and your drains Cornishlass? Willows can be little devils - their roots seek out moisture everywhere.

it'll be fine, as long as its planted 35/40 feet away from the house.

As bamboo has said, 10-12 metres away from houses and drains. They break drains as their roots are attracted by the moisture.

is this even the little ones? as in the grafted type you pick up for under £10?

You'll have to be clearer than that, Laurandben, if you want an accurate answer. If you mean the Kilmarnock Willow, that needs to be a minimum of 6 feet, preferably a bit more, away from a house.