I have not looked to see what advice that you got, but there is no problem with planting this. The whole 'cracking foundations' things is hugely overstated and this is a relatively dwarf form. If you plant it in a pot, the constricted roots will give a very poor tree and you should not bother at all. If it is planted already, just enjoy it. Your house will not fall down.

Thank you for your answer, Vincent.

This is where I found the advice I mentioned:

http://www.growsonyou.com/question/show/7968-is-there-a-problem-planting-a-salix-caprea-pendula-weeping-pussy-willow-nea

Yesterday, I went round a garden open under the National Gardens Scheme, and the owner told me he wouldn't touch Salix in any form with a barge pole........

If you are planting it in a lawn be prepared for difficulties mowing round it. We had a matching pair on our front lawn(s) but dug them up eventually and haven't regretted it. Also they are only decorative for a short time when the catkins are there - have you considered something that will have attractive flowers or foliage for a longer period and be easier to mow or cultivate round? But the roots were certainly not invasive - in fact we were amazed how poorly rooted they were.

Thanks for that. I've already bought the tree, so I'll stick with it, but might add another, more attrctive one later