Your stringToEnglish method only computes a single character so it will never return a valid result for more than that. What you need is a loop, a StringBuilder and a bit of a change in your comparison.

First thing, using a StringBuilder is the best choice for building a string. Strings are immutable so in fact each time you add to one a new instance is returned. StringBuilder is a way around this.

public static String stringToEnglish( String text )
{
    StringBuilder builder = new StringBuilder();
    ...

We also need to notice you have two instances to take care of:

1. When your string starts with a " "
2. When your string a binary "00001"

so the loop you need to process more than a single character would look like...

for (int i = 0; i < text.length() - 4; ++i) { 
...

An optimization would be to jump to the end of the string when it's binary. We also need to consider we are iterating the original string by looking at sub-strings...

if (text.charAt(i) == ' ') {
    continue;
} else if (text.substring(i, i + 5).equalsIgnoreCase("00001")){
    builder.append( "a" );   
}
...

First, we'll see if it begins with a " ", if so continue. Using else if instead of a chain of ifs to avoid needless comparisons. If not, we know it's a binary representation and need to pull it as a sub-string and test it against your "table"; when you find it - append it.

We continue until we've reached the end, as much as we can go, then we will return what we've built...

    return builder.toString() ;
}

You could also use a switch with break ,or better use my suggestion in the commentary, as opposed to the long if chain.