Alternatively, you could file IFR at FL 60 to DRAKE, leave the airway system at DRAKE, and scoot along underneath the airway at up to FL80 in places, descending to stay beneath CAS at GWC. I have done this a couple of times with no problem, provided you stick to correct quadrantals (no radar service available below CAS). I seem to remember being transferred to Lille Approach then Paris Control and then London Info on leaving the airway.
There is no real benefit in trying to stay high once you get over the UK coast as TC will be keen to get you down just north of SAM/GWC to get out of the way of their departures.
The only benefit of going the ORTAC way is the buzz you might get of using your shiny new IR inside the airways system in both directions. The extra miles will cost you a few quid more for that buzz! (This is not a snide comment: I did get a buzz the first few times!)