There are not a great deal of smart door locks on the market in the UK with Yale being the main option on the market. I have recently been made away of Nuki a relatively new business in the world of smart homes, and with an innovative solution to smart locks.
With Yale there is a somewhat complex process to installing the locks, with the Conexis L1 you replace the entire unit including the cylinder, and the smaller Connected Smart Door Lock also requires you to replace the locking mechanism.
The Nuki Smart Lock 2.0 doesn't replace your lock at all but instead, it sits over your lock with the key in it and automatically turns the key. This allows Nuki to have a wider range of installation options while also being considerably easier to install than other smart locks on the market.
Looking over the website, there is one noticeable caveat, if the lock loses power there is no way for you to power it up without being inside the property first. Yale has a 9v battery pin in the bottom of their locks for such instances. The Nuki will warn you when the battery level gets down to 20% so it shouldn't be an issue, and some locks allow you to open the door if the door if a key is inserted on the other side.
If your phone battery dies you can use a unique code on the new Nuki keypad, or alternatively, have a partner open it remotely for you. It is also possible to use a keyfob instead of your phone. The Nuki will also warn you if the door is not shut or locked properly.
The Nuki uses bank-grade encrypted software to protect your phone from thieves getting into your home. I also think it is easier for a thief to bump a lock or smash a window rather than hack a smart lock, so I wouldn't worry about that.
There is a superb level of integration with other smart home systems including Nest, Ring and popular voice assistants Siri, Alexa and Google Assistant. It will even work with Apple Homekit
The Nuki Smart Lock 2.0 is available to order now direct from Nuki and the older version is available on Amazon, so I assume the new one will be available soon.