Hello Christian Lumsden,
Welcome to Microsoft Community.
I'm sorry to learn that your Surface has been stolen.
Although for Windows devices, there is a function to query the device or remotely lock the device:
Find and lock a lost Windows device - Microsoft Support ****
But let me kindly remind you that this is only an auxiliary feature, and that this needs to be used when the location is on:
But let me kindly remind you that this is only an auxiliary feature, and it only works when location services are turned on.
Please allow me to share with you the most correct action at this time, please contact the police immediately and call for surveillance to try to recover your stolen device.
Best Regards,
Mitchell | Microsoft Community Support Specialist