Here's what the RHS has to say about trees and foundations.
https://www.rhs.org.uk/advice/profile?pid=225

All tree roots can damage drains and can spread as far out as they are tall.

Tree roots typically extend out from the trunk about one to one and one-half times the diameter of the canopy of the tree. There are some exceptions, but Araucaria araucana (Monkey Puzzle Tree or Star Pine) roots seem to follow that general rule. Your tree will eventually grow to 30' wide. With this in mind, try to keep it a reasonable distance away from your house so you won't have problems when it matures.

Thanks! I’ll have a good read of that. Most of what I’ve seen seems to suggest with the sort of root system they have, they usually don’t affect foundations of cause subsidence but with it being so near the property, it’s a concern for us.

I'm sorry to be a killjoy but seeing as it is 20 feet high at the moment and has the potential to reach nearly 100 feet, in the distant future and it is only 7 feet away from the property, I would not be happy to keep it. If your heart is set on the property then perhaps have a word with the people next door with a view to having it removed. Also as Honeysuckle suggests it will become very wide and if you have to trim the branches to stop them touching the property, it will become unbalanced and look unsightly.

Ok, thanks for your advice :-)

Well they aren't very pretty anyway (apologies if you like them) but I always think they look out of place in an English landscape. If it were mine I would wave it goodbye.