Steep hills on a Brommie will be tough with standard gearing unless you're a super-athlete. You can always have the gearing lowered but it costs extra. Brommie really best for smallest folded size rather than touring, though of course some might disagree.
Dahon/Tern: I have a Dahon Speed Pro TT. Even with wide-range gearing, would not be my first choice for the type of riding you envision. Fit is not ideal for me and I have some quibbles with the bike's design and handling.
I'm with fietsbob on this one and second the Bike Friday recommendation. Even without dealers nearby, you can have one shipped to you, or if you feel like a road trip, Avon Valley Cycles in the UK could set you up. There is a reason they are the Cadillac of folding bikes - the ability to set one up and build one specifically around you is something most folding manufacturers don't do.