If it is 27R for landings, Myrtle Ave defo isnt the best spot to be at…you’re better off at the roundabout near the BA hangers. This can easily be accessed by getting a bus from Hatton Cross or Central Bus Station, depending on which direction you are coming, and is also free of charge!

As for your travel arrangements, I have found out the following for the 22nd/23rd June…

Train = £152.60rtn (this includes all travel to Heathrow and back again!)

Dep Edinburgh 23.40 (22nd)
Arr London Euston 06.43 (23rd)

Dep London Euston 06:43
Arr London Paddington 07:31 (this won’t take you 45mins, more like 20 mins journey time, but does depend on how smooth your connections are and how busy it is due to rush-hour, so that’s why they allow extra time!;))

Dep London Paddington 07:40
Arr Heathrow Terminal 5 08:01

And on the way back…

Dep Heathrow Terminal 5 22:27
Arr London Paddington 22:49

Dep London Paddington 22:49
Arr London Euston 23:37

Dep London Euston 23:50 (23rd)
Arr Edinburgh 07:16 (24th)

Plane = £188rtn (flying with bmi/BD)

Dep EDI 06:30
Arr LHR 08:00

Dep LHR 21:00
Arr 22:20

So, although the flights are more expensive, its not that much more, and as others have already suggested, the plane will take you direct to LHR and back again, whereas the train involves various stops and connections…just a thought worth taking into consideration?!

Hope this all helps.:cool: