Thatch is naturally occurring and is essential for a healthy lawn, however too much can have the opposite effect.
Once you have removed the thatch and moss from your lawn it is important that you encourage the grass to grow. Where there have been areas of moss in your lawn, add a good quality moss killer to the grass to prevent it from returning. Add a good lawn fertiliser to the rest of your lawn to encourage the grass to grow and water for the next few days or as required. This will help the grass grow thicker and more quickly.