There is a read file component that lets you read a file into the stream and then attatch it to an email. The issue will be making sure your process has rights to the file path. In the debugger, it runs under your user context, but once published, it runs with Network Service.
To overcome this in a Forms Start workflow, you need to create a new application pool and have a named user as the application pool identity. Make sure that user has right to the file path.
Rob