You can always use unicode-regex-range-character-class.pl

space => [\u0009-\u000D\u0020\u0085\u00A0\u1680\u180E\u2000-\u200A\u20
+28-\u2029\u202F\u205F\u3000]
[download]

so

$ perl -pe " s{\\u(....)}{\\x{$1}}g "
[\u0009-\u000D\u0020\u0085\u00A0\u1680\u180E\u2000-\u200A\u2028-\u2029
+\u202F\u205F\u3000]
[\x{0009}-\x{000D}\x{0020}\x{0085}\x{00A0}\x{1680}\x{180E}\x{2000}-\x{
+200A}\x{2028}-\x{2029}\x{202F}\x{205F}\x{3000}]
[download]

Thus

#!/usr/bin/perl --
use warnings;use strict;
use Data::Dump;
$_ = qq{\xC2\xA01.00};;
utf8::decode($_);
dd[$_];
s{^[\x{0009}-\x{000D}\x{0020}\x{0085}\x{00A0}\x{1680}\x{180E}\x{2000}-
+\x{200A}\x{2028}-\x{2029}\x{202F}\x{205F}\x{3000}]+}{}g;
dd[$_];
__END__
["\xA01.00"]
["1.00"]
[download]

Although, in 5.10 you could probably just use  s{^\p{space}+}{}g;