When I was at school in the 80s, I read a book where two children has
to run away from their village. The boy had 6 fingered hands and/or
feet. The girl was telepathic. They run to the woods and hide with
other disabled people. Police/army want there to kill them. A lot were
killed but the girl, boy and others were picked up by helicopter from
people who live in another country (Australia).

I believe your book is "The Chrysalids," by John Wyndham (a pen name
of John Wyndham Parkes Lucas Beynon Harris). The book has also been
published under the title "Re-Birth."

"In John Wyndham's The Chrysalids, post-holocaust radiation led to
minor mutations such as six toes, or telepathy. Those who deviated
from the norm, even those who looked normal--perhaps especially those
who looked normal--were hunted down and killed."

Nicola on the Web: The New Aliens of Science Fiction
http://www.nicolagriffith.com/aliens.html

"The community David belongs to is a very strait-laced one, who
insists on 'purity' and conformity to the 'True Image'. Every
deviation (i.e. mutation due to radiation) in either human, animal or
plant is rooted out mercilessly. Plants and animals are burned, people
get sent to the savage, untamed 'Fringes'. Physical deviation, that
is. The powers-that-be don't realize that a group of children have
developed telepathy. They look totally normal, but they're able to
communicate with each other without words and over distances. They
learn very early that 'different is deadly' and protect themselves
carefully but get betrayed by one of their own, who falls in love with
a Normal and entrusts him with their secret, and also, unwittingly, by
David's little sister Petra who's the most powerful telepath ever seen
with powers that develop before she's old enough to learn control, the
result being they have to flee into the Fringes."

Amazon: The Chrysalids
http://www.amazon.com/Chrysalids-John-Wyndham/dp/0140013083

"The Chrysalids (U.S. title: Re-Birth) is a science fiction novel
(ISBN 0-7487-4286-7) by John Wyndham, first published in 1955. It is
the least typical of Wyndham's major novels, but is often, along with
The Day of the Triffids, cited as his best.

The story is narrated by a boy, David Strorm, whose early friendship
with Sophie, a girl who must conceal the fact that she has six toes on
each foot, causes him to realize that 'Deviations' are more common
than is generally acknowledged. David's own father is a religious
patriarch and a zealous and brutal enforcer of the persecution of
human deviations. Slowly David comes to question why anyone who is
different must be persecuted. Later, along with certain other children
his age, including a cousin with whom he falls in love, he discovers
that he has telepathic abilities. Growing up in the Labrador society,
David and his fellow telepaths realize that their unusual abilities
technically make them mutants and that they must hide these abilities
on pain of ostracism or death. The fact that their mutation cannot be
directly detected allows them to live within the society for a time,
but not indefinitely, which becomes more apparent as they age.
Eventually the group is exposed, and a posse led by David's father
tracks down the members one by one. David and his cousin and sister
must flee to the Fringes. Through their telepathic abilities, however,
they make contact with a more advanced society in faraway 'Sealand'.
The ending finds them imminently to be rescued by airplane and hopeful
about a better life in a place where the abilities that make them
outcast in their own society will be not only accepted but
commonplace."

Wikipedia: The Chrysalids
http://en.wikipedia.org/wiki/The_Chrysalids

"As a child, David makes friends with Sophie, a girl who has six toes
on each foot. Her parents have hidden her from the authorities and
they beg David not to tell. When their secret is accidentally
discovered, David sees at first hand the relentless cruelty of the
society in which he lives. However, he has his own secret. David is
one of a group of children who can communicate with each other
telepathically. He is, therefore, himself a ?Deviation?. He also has
strange dreams of a city with skyscrapers, horseless vehicles and
flying machines. David and the others struggle to keep their telepathy
a secret, but eventually they come under suspicion when it becomes
clear that David?s younger sister, Petra, has even greater powers.
Being a young child, she has little ability to control her thoughts
and no real awareness of the dangers they present. Eventually the
authorities come to arrest the group and they have to flee into the
Fringes, pursued by David?s father and the other men. Petra then
starts receiving telepathic communications from someone a very long
way away. The others cannot hear the messages, but Petra says that
they are coming from a woman in a place called Sealand far to the
south. It transpires that this is the advanced industrialised society
of David?s dreams, where everyone is telepathic. The woman rescues
them by helicopter in the middle of a battle."

Penguin Readers Factsheet: The Chrysalids 
http://www.penguinreaders.com/downloads/0582419808.pdf

If you are interested in purchasing a copy of "The Chrysalids," these
links may be helpful:

ABEbooks: John Wyndham, The Chrysalids
http://www.abebooks.com/servlet/SearchResults?sts=t&an=john+wyndham&y=0&tn=the+chrysalids&x=0

ABEbooks: John Wyndham, Re-Birth
http://www.abebooks.com/servlet/SearchResults?sts=t&an=john+wyndham&y=0&tn=re-birth&x=0

My Google search strategy:

Google Web Search: chrysalids "six toes OR toed" telepathy OR telepathic
://www.google.com/search?hl=en&q=chrysalids+%22six+toes+OR+toed%22+telepathy+OR+telepathic

I hope this is the right book! If it is not, please request
clarification; I'll be glad to offer further assistance before you
rate my answer.

Best regards,
pinkfreud

Very quick answer. I am very happy now and can now buy the book. Thank you