Hi Scottie
I'm new to HU too and glad to hear you're so enthusiastic about your first trip and welcome to the motorcycling fraternity!
I and many others on here will agree with your girlfriend that it all is a bit of an obsession and once the bug bites, your girlfriend may become a lonely lady, unless she mounts up and joins you on the forthcoming advetures you have in store.
For a real pannier packing insight into what you may get into, buy a great read, "Uneasy Rider by Mike Carter" as a non biking 42 year old, entering his (first?) mid life crisis stage, he passes his test and a month later wobbles off towards Europe on an R1200GS and writes a hilarious account of his brilliant first attempt that covers 20,000 miles in 6 months, that sees him ride to Mount Arafat and back!
However, although Mike Carter got away with it, the only reservation I have about your first journey is that you are doing it on an R1200GS, a great all rounder, but just about the biggest bike out there, apart from Wings and things!
As for taking it off road, I would say you'd need a few hundred miles under your belt before contemplating that ambitious undertaking, as you may find out the hard way how much BMW's test ride insurance excess is!
Mind you, I'm only 5'10" and about 14 stone and find them a little intimidating, but fantastic once on the move. However, if you are a big bloke, say 6' plus, with relative weight and long legs, then you should find the bike easier to handle then us shorties.
Perhaps you should switch your first ride to a F800 GS, as that's what I would be looking at if I was buying a new BM to tour on, a lightweight twin, that can cope with all that a tour has to offer, plus has the badly needed extra horses compared to the F650GS. Did your BM dealer offer this as an alternative?
Just some friendly advice from a life long biker and if you are plotting a route that takes you through the Cotswolds, you are welcome to call in for a cuppa and a sarnie.
We are between Chipping Norton and Banbury, Oxon and if I were you, I'd leave the camping for later on in the year, as I can book you in at the Ellie, one of our local pubs for about £25 B&B for one night, one person or a bit more if the other half decideds to join you.
Good luck with your trip and look forward to reading about it when you return.
Cheers
Chris
01295 722272