The third option to import is to import individual addresses and private keys; not for you.
What did you use to generate the seed? Some hardware wallets could be using differing standards/derivation paths to generate your addresses and that could be a problem. If you've generated it using Electrum, choose Standard Wallet and I already have a seed after that.
I have the original Bitcoin Core.
I thought that BCH has a separate address thats related to its forked BTC address, is that not true?
Since the fork I've only sent a small amount of BTC once - that's not going to mess with my attempts to claim the BCH, right?