Tom, you're reading a great book and the above posts contain a lot of
good advice. If you have access to experienced mentors with a decent
performing dual ship, definitely take advantage of that. It may not
help with the butterflies much, but you'll probably learn a lot.
There is no substitute for taking that step away from the safety net
on your own. I own a Duo and take less experienced pilots up any
time I can and I've done a lot of coaching from the back seat since
buying it. 300+km flights often end with big smiles and amazing
stories for them, but the first time that they get out of glide from
the airport and make it back on their own, it is a whole different
world of ear-to-ear grins, even if it was only 10 or 15 miles away.

Planning and preparation will probably help with the fear more than
anything. Confidence in your ability to land the glider exactly where
you want at minimum energy without using the altimeter is critical in
my mind. If you have very solid thermalling skills, make sure that
you are launching early and landing late or flying on weak days so
that you experience weaker lift. Being very good at finding and
working weak and broken lift will also boost your confidence since it
means you'll be less likely to need your landout skills. Plan your
route. Fly it with someone in a dual ship if possible so that they
can point out common places for lift or sink or the good landing
options. If they will let you, be responsible for as many of the
decisions as possible when you fly it. Drive the route, check out the
landing options on foot if possible. The fewer variables you have to
consider on your first flight, the more confident you will be.

Finally, apprehension and nerves are a good thing and we've all
experienced them at some point or even routinely. I find that as I
head out XC and I'm getting towards the edge of gliding range back to
home, my brain switches over when the glide computer (or your Mk I
eyeball) says we are out of reach. It's very liberating, since no
longer is the home airport a concern, because you can't just glide
back to it.

Hopefully you have access to good mentors and instructors that know
you, your skills and your desire to get into XC. Make sure you're
asking the same questions of them as you are here.

Morgan