Interior conservatory blinds can make a huge difference to heat gain and loss in a conservatory, especially when modern solar reflective fabrics are used. But for real heat reflection, particularly in the hottest summer months and especially if you have a south-facing conservatory, the best solution is an exterior conservatory blind or awning.
They are easier to fit if you have a lean to conservatory lean-to conservatory when the headbox of the awning can be attached to the wall of the property and then run flush with the sloping glazing. But they can also be fitted to gabled conservatories with forethought and planning.
Conservatory awnings are usually electrically controlled from remote units and use mesh fabrics that will allow some light through while reflecting heat. Traditional fabric awnings are more decorative but are less efficient at reflecting heat.