https://iancoleman.github.io/bip39/. Download a local copy and then use it. You can see it generate same address you have in your wallet. You can also use Electrum, Mycelium or Bither to recover your Bitcoin from seed.

Blockchain.info is now an HD wallet. If you don't know what that means, read http://support.mycelium.com/hc/en-us/articles/207045475-What-does-HD-in-HD-Wallet-mean and/or http://www.fintechblue.com/2016/03/what-is-an-hd-wallet/.

The password you are referring to is the one you use to sign in, right? If so, when you recover later, if password is asked, don't enter any because you don't need password to recover from a seed.

Note: Create a new wallet in Blockchain.info for testing. Don't expose seed or send it to anyone. Getting your seed means having access to your Bitcoin, just like private key.

Edit: if you just want to check whether the addresses created in another wallet is same as in Blockchain.info, then you can use xPub key. To do it, follow:
  • Go to blockchain.info/wallet and login.
  • Click menu.
  • Click 'Settings'.
  • Click 'Addresses'.
  • Click 'Manage' of the wallet you use or want to export your xPub key.
  • Click 'More Options' and select 'Show Xpub' from drop-down list.
  • Click 'Confirm'. The long time starting with "xpub" is extended public key(xPub) of that account.
  • Copy/save your xPub.
  • Now, go to iancoleman.github.io/bip39/ or open local file if you have downloaded it(recommended).
  • Paste xPub in 'BIP32 Root Key'.
  • Select 'BIP32' in 'Derivation Path'.
  • Addresses will now be created and you can see your addresses in generated ones.

Note: Your xPub must never be shared with people other than you trust because once someone has your xPub, they can track all your transactions corresponding to that key.