Probably you should retrieve the extended private key (or use the pass phrase you have remembered) from when you created the online wallet and create a new BTC wallet with the same information. You might want to do this with a wallet where you have more control on and which is local like Mycelium for Android. Then the address should be in that wallet and the funds as well.

I think it will be on the same address but on regular bitcoin network not bitcoin cash.

As far as I can tell, bitcoin and bitcoin cash utilize the same wallet addressing scheme, ie an elliptical curve sighnable public key generated from a private key utilizing the same curve, field, etc. So being that coinbase does not yet support bitcoin cash, I presume it used the address provided but on the bitcoin network, the transaction was mined onto the block chain for bitcoin.

If my assumption correct, your bitcoins are now at the new wallet. You MUST be able to recover the private key used to generate that address if you do not have it; it is needed to spend bitcoins from that wallet.

As for your bitcoin cash, they are then on a separate blockchain for bitcoin cash. They will remain at the address kept by coinbase. You will not be able to take control of them until either coinbase releases that address, or make them available some other way. I have read coinbase plans to do so in January. Probably based on their market cap.