Call your insurance then an arborist

We ended up calling the Works Department and the lady (believe her name was Lucille) was extremely helpful. Our call on a Thursday was met with staff being on site the following Monday or Tuesday and due to the serious nature of the tree cracks (well beyond even what we had found) there was approval and instruction for the contractor to remove the tree immediately. That same day the vast majority of the tree was taken down and the site cleaned with remaining work done the next day. All the people involved were wonderful, efficient and very professional - we (neighbours included) would like to thank everyone!