Of the offers live on this counter at the moment, the one worth planning around is the Tuesday drinks offer: buy one, get one.
No code to remember
It is configured on the items themselves, so the register applies it. There is nothing to type at checkout and nothing to show on your phone — which is the main reason it is worth mentioning at all, since the offers that fail are the ones that require you to remember something.
There is also a buy-one-get-one at 50% off
A second offer takes half off a second item. Like the drinks one, it applies at the item level rather than to the whole basket.
Where to check what is actually running
The offers page. It is generated from the account, so it lists what is live right now rather than what was live when somebody last updated the site. If an offer ends, it disappears from that page on its own.