Hi Lisa S.H
I use a Cable lock with it's own inbuilt lock for keys. The lock came with two keys so I leave one at work where I cycle to the most and one on my work keychain. Reason being if I ever forget my workkeys I can still get in from people letting me in and then grab the key.
The other thing is the bike lock up is in a "coded" bike lock up. so I leave the cable there overnight. It's about 1.5cm wide (almost an inch) thick.
My BF and I also have a U lock which we use on the weekends, big enough to lock up both bikes to a rack. ^_^
