How to put spots lights in a flat (false celling) without losing to much height.

As you have another property above the spotlights will need to be fire rated to comply with building regulations. For your own safety please see; http://www.esc.org.uk/public/guides-and-advice/ and; http://www.esc.org.uk/fileadmin/user_upload/documents/public/leaflets/DownlightConsumerWEb16.10.pdf I would disagree slightly with substructure as generally its much easier to lift the floorboards in the room above (in your case someone eleses flat!) to access the ceiling void so the new cables can be installed for the spotlights. Whilst they can be installed from below, many more holes will be needed so you will end up having to skin the ceiling with plaster to make it smooth after the cables have been installed and holes have been cut out for the spotlights. Hope this helps, please click on "like" if it does.

the only reason you would need a false cieling was if the floors are concrete are they?,if not get an electrician in ,he will get them in the existing cieling void without any disturbance to upstairs