as far as I knoww UVMM doesn’t support LXC containers. If you want to use them, you’ll have to manage them manually. There’s not much to observe regarding UCS on top of what you generally have to do with LXC; just use it.
However, I suggest you take a look at another product as the OS for your virtualization host, especially if you want to mix contains & full VMs: Proxmox. It’s a free-with-optionally-paid-support type of product that allows web-based management of both KVM and LXC VMs/machines. It can use advanced features like snapshotting, iSCSI, ZFS etc.
Univention’s UVMM solution is nice for what it does, but it’s also very limited regarding the features offered.