My initial instinct is that it means what it says, i.e. no DME, no approach, though we all know that there are plenty of people out there using GPS for the DME reading without saying anything.
Some approaches say in the notes 'No DME: radar ranges will be passed at Xnm outbound and Ynm inbound); not at Blackpool, I see. Only the NDB/DME actually says 'DME mandatory', though, on my set of charts (AERAD), presumably because of the high ground to the east.
Interesting to note that the Manston LLZ/DME/NDB approach to Rwy 10 says:
3. NO DME. Advise ATC. Rdr Ranges given at 10nm outbound and 7nm & 5nm inbound...
4. DME mandatory
which makes little sense...
Final thought: why not just get an SRA? Or do you have an IR so can go to 200ft on the ILS (SRA minimum for 28 being 500ft)?
Tim