there you go.
somebody improved on the script for showing a maintenance page posted here http://forum.mikrotik.com/t/hotspot-login-redirect-page-without-internet/78594/30
and posted at this site https://buy.guru
it works perfectly and works flawlessly, attaching the direct link to script here.
but as written do remember to create a second folder and populate it, else it wont work!
https://buy.guru/script-hotspot-mikrotik-maintenancepage/