Identify a tree

Glasgow, United Kingdom

I am looking to see if anyone can help identify this tree. I have just recently discovered that I am into gardening in a big way! I live in a flat which is situated with beautiful mature grounds however the grounds are not being maintained the way they used to......I will post more on that later. I don't have any close-up photos of the tree but I have attached the most close up one I have. The tree is now approx 25 feet high and it spreads like a big umbrella about 20 feet in diameter all spindly and wavey it has long pointy leaves and right now they are starting to get tiny creamy flowers which when it is windy fall like snow. In the winter it goes totally bald. The trunk is in several stalks the thickest one about 4 inches diameter. I love this tree the reason I want to find out about it is the gardeners (so-called) I have my doubts, chopped a lot of branches from it and I am terrified I come n from work one day and it is hacked to nothing. My cats like to sit on the trunk parts, as the trunk has grown up to about 4 feet then grown sideways so it is a nice wee seat for them. Thanks for any info I can get. I have loads more questions about how to plan my garden as I want to plan it the gardeners just maintain the minimum.