So if I mix my coins in the wallet then when sending them out use "coin control" to select the mixed coins is there then any need to use "private send" when sending ?
Yes. Using PrivateSend ensures that there is no change address that could potentially be used by a future attacker to link your addresses to a single wallet. It selects the best possible denominations to match the amount you are trying to send, and sends the remainder to the miner as a fee.
I often use coin control together with PrivateSend so that I can send the whole amount (and avoid paying up to 0.01 fee) by copying the value in "After Fee" field. If you do that then technically there is no difference whether you have PrivateSend enabled or not because you are not receiving any change anyway. However, as strophy suggested, it is better to have PrivateSend enabled to ensure that you don't accidentally receive any change or use unmixed inputs.