Welcome
I moved your post from the Welcome thread as it's a good one.
Yes, ficus trees can cause many problems and with the recent amount of research I have done on tree roots and there impact upon soil and structures you have plenty of ammo.
First of all, yes, I suffer from rashes from these trees, caused from the dust/sawdust/sap. However in the authorities eyes they may think providing the tree isn't cut you wont suffer the problem.
More info on that here.
Photo dermatitis from ficus sap, and there's others too.
There's many types of ficus trees, you need to get it identified, take some pics, close up of leaves and overall. We will then be able to inform you of the mature size.
They have an aggressive root system which can easily travel 7x the drip line of the tree.
Also you need to know what type of foundation and soil the house has. Tree roots can go beneath a raft slab and extract moisture. On a reactive clay soil the raft slab may subside and the house cracks (if made of brick). Cracks generally start from corners and windows/doors etc and travel along the mortar lines of the brick. Look carefully over the house and see.
There's this thread on soil subsidence and trees.
Soil subsidence and trees
So, if you are to take on the authorities so you can remove this tree then you need to do some research and supply some data. Then hit them between the eyes.
In extreme circumstances authorities may argue that if root barrier and pruning were undertaken the tree could stay for many years ... that would be their only saviour. In response to that and the long term costs and maintenance as root barrier doesn't last forever is offering a replacement planting, something more suitable.
Failing all of the above, also discreetly find out if dead trees are protected or deemed hazardous and removed.
