Interesting graphic, FE21, thanks for that.
As befits the somewhat dumbed-down approach of the your.heathrow.com website (whose Heathrow?) that it's from, the low-resolution image is rather lacking in detail, in fact it doesn't show any ground transport infrastructure at all other than present-day roads, so we're none the wiser about the proposed M25/M4/A4 layout.
Some interesting changes to the airside layout, though, compared to the previously published NW Option 2 proposal:
a) the T5/T6 complex is now shown as occupying an "island", with taxiways on all 4 sides
b) all 6 runway ends now show significantly displaced landing thresholds, presumably for noise mitigation reasons