Question: I have just discovered that you can do both a combined smart contract that includes both the token and the crowdsale OR have the token in a separate contract from the crowdsale contract.

Can anyone tell me what the advantages are to either of these methods please?

Many Thanks,

Phil.

Answer: 
This is not the answer to the question, but I would like to add this to the previous answers.

When you commit your transaction, Ethereum client calculates, how much transaction would cost if transaction uses all provided gas up to gas limit.

So, if you have gas limit set to `6,700,000` and gas price set to `20 gwei`, then client would require you to have at least `0.134 ETH` on your wallet. I am unsure if it is possible to disable this check.

You can try lowering gas limit for your transactions or gas price, but this would cause longer confirmation time
My approach is:

1. Deploy to a testnet like ropsten and note the gas used
2. Go to <https://web3-tools.com/> and type in the gas to back-calculate the gas required in USD

Like the accepted answer, my basic contract was about 1,400,000 (compared to 21,000) for a transfer

Disclosure: I wrote web3-tools.com