As I'd already be with London Control, getting VFR flight following, my RT would be:
London, N12345 request
N12345 go ahead
N12345 request IFR to Heathrow
Roger standby
N12345 is cleared to Heathrow, turn left heading 160, join V363, climb and maintain 5000, sqwark 4462
Then it'd be:
N12345 turn left heading 050 maintain 2000 until established cleared for the ILS 9R approach. Contact the tower at the outer marked good day.....
easy peasy japaneasy
there I go, dreaming again