gawk-sed

Here is the command:

awk '{gsub(/\n\n+/,"\n\n");printf $0}' RS="^$" $1 | sed '
s/\s*\([.,;!?]\)\s*/\1 /g
s/\s\+/ /g
s/^.*$/\L&/
s/\([.;!?]\s*\)\(.\)/\1\u\2/g
s/^./\u&/
/\(^$\)\|\([!?;.,]\s*$\)/! s/\s*$/.&/  #C3

And here is the output:

I need to go to london, after i reach the; Uk.

But i need five hours? To reach it.