preparing plants for outdoors

when growing outdoors in the uk, ive bin told its best to prepare them indoors first for about a month, can some one please tell me if it is completely neccessary to get them used to outside first by keep putting them outdoors in the day whilst vegging them, because live in a flat n have no garden so this option is not open for me, will the cold nights shock them and kill them if there not use dto the temperatures and will a fan be sufficient enuff to prepare them for outdoors? ALSO IS VEGGING THEM FOR 24 HOURS A BAD IDEAE IF THERE GOING OUTDOORS? SOMEBODY PLS HELP!?

YOu want to harden off(putting them outside fora couple hours a day) so they dont get stressed.

Im sure you'll be fine just do what you can for the babies, remember what ever you CAN do, can make the bud that much better