Can someone please tell me what the plants in the photos are?

the surrounding darker plant looks like an oxalis?
Pretty, but I think you have to be firm with it if its anything like ours.

Yes, it'll have a small yellow flower too. In the middle is a type of rockery Sedum or Stonecrop, makes a great ground cover in a sunny border.....:o)

Sorry, dont know this one, Norrms

As said the one round the outside is Oxalis. O. cornuta. It is an absolute thug which spreads everywhere and is very hard to get rid of.
The other is Sedum acre.

Yes the Oxalis does spread like wildfire the seed pods are like mini peas which pop open seed fly everywhere.