Hi Andrew,
You are using asp.net so you can use RDLC for your reporting. Now if you want to know about RDLC or how to work with RDLC in Asp.net take a look at following link:
Creating RDLC Report in Asp.Net

You can save those reports as PDF manually(as there is an option in the report viewer) or by code. I am sharing some code snippets which you can use for your solution.
For converting your reports to a PDF:

  private string ExportReportToPDF(string reportNamewithFullPath)
    {
       Warning[] warnings;
       string[] streamids;
       string mimeType;
       string encoding;
       string filenameExtension;
       byte[] bytes = ReportViewer1.LocalReport.Render(
          "PDF", null, out mimeType, out encoding, out filenameExtension,
           out streamids, out warnings);

       string filename = Path.Combine(Path.GetTempPath(), reportNamewithFullPath);
       using (var fs = new FileStream(filename, FileMode.Create))
       {
          fs.Write(bytes, 0, bytes.Length);
          fs.Close();
       }

       return filename;
    }

For sending that pdf via mail:

private void BtnSendByMail_Click(object sender, EventArgs e)
{
      Mail mail = sendMailView.CurrentItem;//some mail helper class. you can use your own
      mail.AttachmentFiles.Add(ExportReportToPDF(yourRdlcReportPath));
      mail.DeleteFilesAfterSend = true;
      mail.RequireAutentication = true;
      mail.Send();
}

So these are the two methods which you can combine to create complete code as per your requirement.