It is getting a bit late for planting herbaceous perennials like these outside in the UK. I would plant them in ordinary potting compost in pots and keep them somewhere frost free, but cool until March/April. The pots only need to be a little larger than the root ball of the plant and they need to be kept just on the damp side of dry, not waterlogged.
If you live in a mild area of Britain, say Cornwall or West Scotland then you can plant them in the garden now.