Sure, you just need a device that has a radio that communicates with smartthings and has “dry contacts.“ (That’s what they are called in the US, I’m not sure if there’s a different term in the UK.) Dry contacts are dry because they don’t contribute to the current on their own. So they’re very useful for adding inline to an existing current branch and then having something happen when current comes through that line. There are even some devices designed specifically for that, but more often it’s a contact sensor or a tilt sensor that can also do this.
You will need to get a device specifically for Europe/UK, because of the voltage differences, and of course regional frequencies if it’s a Z wave device, but you will still have quite a few choices. 
See the following FAQ,
FAQ: List of devices with dry contact input from external sources
As far as the specific use case with the outside security lights, you might also be able to just use a battery powered lux sensor limited to the time between sunset and sunrise and then alert when the lux level went up. so just another option.