U-lock or Disc lock?

[slappy]

If you have a permanent spot that you always use then take in a 19mm thick link chain and leave it padlocked there. I say leave it because its too heavy to take in and carry around every day

Thieves are wise to that, they see the chain and lock there with no bike and superglue / araldite or damage the lock so it will not work. You arrive at your usual spot to find the lock unusable and leave the bike with no chain locking it, just what the thieves want you to do, as you need to get to work on time, thieves come along and nick the now unchained bike.