Hi Si,
Dont know about rates of descent, but I can tell you about the Manchester-London routing...
The CONGA sids at Manchester 24 went out after Runway 2 was built, we now have HONILEY departures off the 24s. CONGA SIDS do still exist off the 06s, but if we are going off 24L then a Honiley 1 Yankee departure is used by the shuttles, with an initial climb altitude of 5000 feet, turning right to route around Knutsford (at the request of the eco-warriors) and then left to track the HONILEY VOR, picking up the Bovingdon STAR for Heathrow. Typical cruise altitude is between FL180 and FL280.
The Bovingdon STARS consist of routing EGCC-HONILEY-WESTCOTT(NDB)-BOVINGDON-EGLL. Aircraft leave Bovingdon for Radar Vectors to the runway, and holding will take place either at BOVVA or Bovingdon, both at pretty much the same points. Knowing Heathrow, you'll probably get 160 knots to 4DME.
Hope this answers all you questions,
Cheers
G-BPEC