Hi guys,
I'm new to the BTC scene and have just started buying some of the coins available on coinbase in the UK.. I have left BTC and ETH on the wallets on Coinbase for now but I've transferred some LTC to my Electrum wallet, I used the receive function to generate a key and then put that in Coinbase to send to it. I believe I didn't have my wallet 'open' or online at the time so I'm not sure if this means I did not 'receive' it or it will show up later, I've tried restarting the wallet but no luck. Have I made a newbie mistake and lost the transaction? Thanks in advance.
You can be off line and will be able to receive your coins. Every address is public and every single one of them exist in the network.
Have you used litecoin electrum?
As everything is public you can try to enter your litecoin address on this website:
https://chain.so/ and tell us what happens at end. This chain.so is a simple blockchain explorer that runs a node and by doing that it has access to all records of transaction that happen on the blockchain. If it shows you have your coin then you are good as it is most likely problem with litecoin electrum. But if it doesn't show any coins try to go to coinbase and see in case you miss typed the address.
Cheers, tell us what happened at end so I and others can tell you what could be done if it can be done.