I need some advice. We're moving my son up to the loft conversion bedroom and want to replace the blinds on velux windows. Question is which ones would you recommend? Ideally up there we want blackout and also anything that can reduce heat. What have you found really great? Inside or outside? Any ways also to block light when windows are open for air? If any reduce heat do they do so to the extent we wouldnt need an air con unit up there in a heatwave and could just use a fan? Don't mind paying more if that is the case. Thankyou! Plus, Would you recommend getting them from Velux or elsewhere?