There are not that many places where you can't fly airways to and certainly the routing you have described is easily done on the airways albeit at the cost of a little extra time.
Bose
This was a double trip ie I did both there and back in the morning with no problems and most of the trip airways.
The return was all radar headings which ended up sending me in a large oval south west not on my filed route.
I ended up down near compton. To stay airways from there would have required a routing to BCN and then north. Quite a long way especially as I had already made a tour of the UK keeping london control happy.
In future maybe London Mil if Brize are no longer playing
Pace