Hi Pace - I still think you are a little confused about the new EASA land (aren't we all). The IMCR replacement is in name only and does NOT give you any new en route privileges outside the UK or inside the UK - this is the purpose of the new additional en-route EIR rating. This is an entirely separate rating which covers airways flying etc.
If you bolt the EIR onto your existing IMC (now known as an IR(R)), then with BOTH ratings you do indeed have fairly reasonable privileges, which will include airways and certain approaches, in the UK only.
If you don't take the new EIR then nothing has changed from where we are today.
Cheers