In the UK, there are two main DMR networks the DMARC based Phoenix and Brandmeister Networks and a number of smaller networks such as the South West Cluster, Salop Cluster, Xtend Network, Northern Cluster and some stand alone repeaters. All the Amateur DMR radios are capable of working with all these networks and they can ALL be programmed into your radio, you are NOT tied to any one network. You only need the repeaters you can work from your location programmed into your radio, the distant repeaters do not need to be programmed in. for example if from your base station you only have one repeater available to you, that's the only one you need to programme in in order to work all the repeaters on the network your home repeater is on.
For further information gleaned from the Public domain visit
Brandmeister UK Network DMR Repeater