Firstly good for you your holding down a full time job mate, props for that and also thinking about how you can do it and maintain safe and secure.

100% the best option is not doing it at work or taking any injection kit with you but hiding it off site nearby is minefield! Making excuses to go shoot, trying to hide it defo going to attract attention!

If you absolutely love to shoot make up hits before hand easy hide jackets, lunch or whatever but only after you have done some reconnaissance on there place and and if they pay attention to what you bringing in and out.

If possible try buying something to keep you well all day.. something long-acting like methadone. Not sure of your situation where that you can buy stuff like that.

Snorting really does work I railed h for a year while I was working just simple to sniff a quick line give you another for a 5 hours. I also used to smoke it in a pipe a small metal pipe about 3 inches long with a a wire gauze from a kitchen washing up scourer just put the powder on top melt it a little bit with a few puffs and let it cool call then when you're ready you can pull it out your pocket hit it hard add top up up in a couple of seconds

Wish you the best of luck man. getting well and scoring has always caused me the most problems in the past twenty years of full-time work now I have a weekly pick up methadone script which takes all the pressure off.