I have suffered from agoraphobia for 28 years. Although agoraphobia is described as a fear or open spaces or fear of the market place (latin) it is really a fear of being too far from a place of safety (home, car, office etc.)
There is no treatment available on the NHS or privately for agoraphobia other than mindfullness or 10 sessions of CBT. Both are hopeless inadequate.
At the worst my agoraphobia meant that I could not walk further than 150 yards from a place of safely. After 6 months five times a week exposure work with CBT I extended that to flying to Cyprus.
Unfortunately phobias are only symptoms of a illness and slowly my phobia got worse till all train and tube travel ceased, as did flights.
It is something that I battle with every day. I have managed to accept that perhaps me and travel do not mix.
See http://www.highanxieties.org/agoraphobia for more details