After I printed out the piece of paper I went to fund it after about 10 minutes.
I went to bitaddress.org then switched off my wifi connection and generated 3 codes and printed out the 4th one, then about 10 minutes later I went to fund it with 6 BTC using the public address.
But know for some reason blockchain is telling me the private key is invalid?
How long did you wait between these last two steps? Did you confirm that the bitcoins were send to the public address? How many confirmations do they have?
It has been a few hours since then and last time I looked there was 13 confirmations on the public address.
I should add when I go to bitaddress.org and into wallet details I enter the private key and it shows not found so that is what has me worried.