If i get interior lights they will be designed to connect to the cigarette lighter. how is the best way to connect them to the battery with a switch added so i can turn them off when i want to ?

Get usb ones not cig lighter. Wire up a 12v-5v dual USB into the pos and neg of your radio harness and wire them behind the dash! Thats what I did for mine  

 

https://www.ebay.co.uk/itm/Car-DC-12V-to-5V-3A-15W-Hard-Wired-Dual-USB-Charger-for-Dash-Cam-iPhone-GPS-DVR/183256477134?epid=22010372892&hash=item2aaaefedce:g:5Y4AAOSwSEZa8AtF 

https://www.ebay.co.uk/itm/48-LED-Car-Interior-Lights-with-USB-Port-and-Car-Charger-Waterproof-Multi-color/253572999332?hash=item3b0a20e8a4:g:Oh0AAOSwigla2aAc

 

This will also mean it will run on ignition power not constant live like the ciq socket is.