Yay!! Another GHD user. Whether you use a heat protector or not, your hair will be silky smooth with the GHD. I have never heard anyone say the GHD made their hair feel like straw. I recommend using a heat protector spray or cream just because it helps a little. In the end, we will all get split ends (*sob*) and damaged hair even if we tried to prevent it with our heat protectors. Styling products WILL damage your hair, you cannot change that, but to lessen the effect of the damage done by the heat, I recommend you use a heat protector.
The GHD thermal protector will work fine, just spray a little, you do not need a lot.