''I'll pick up a multi speed fan from the local DIY shop.'' so is that it for ventillation? Are you planning on having that blowing it your grow room over the bulb ? The light is good, yeah you can use it throughout the whole grow, you'll come to realise that the heat really needs to be dealt with, (taken out) or your looking at temperatures into the 90's and above, are you going to be using an extraction fan?