Have a 24hr local locksmith hold on to a set of extra keys for the unit. 

You can also check with locksmith Westcombe Park, they might have a better idea of which lock will work best in your area and they can also install the lock for you.

You can also authorize her to get a locksmith to change the locks and give you a copy of the keys. 

I use a system similar to landlord locks but I had a local locksmith do it.

I need to get some more keys cut (a perennial for landlords seems to be getting keys cut at the locksmiths).

When something serious goes awry either they or you will contact the contractor, plumber, electrician, locksmith to have the problem resolved. 

So easy to change the code when a roommate moves out and you never have to worry about a dumb tenant losing their key and having to deal with a locksmith or leaving work to let them in the house.The house doesn't have a living room or any additional things like tv's. 

We are contacting them, in the meantime I need a contractor to make sure we are not out of code and a locksmith to fix the forced entry the cops made.

The tenant has threatened me before in the past over text messages but has been civil in person.I was going to give notice to enter the unit and schedule a locksmith (to open the storm door) and hopefully change the lock in the storm door so we can both have keys, and schedule a police officer for a civil standby.  

Is there a better option such as getting a locksmith?