One word of caution with the online option. I used a different vendor to the one mentioned above, but all the blinds supplied were 25-30mm narrower than the measurements I provided. I presume this is to minimise returns, and the brackets allowed adjustment so they could be fitted, but if you're looking for blackout, the blinds need to be spot on to ensure there is no light leakage at the sides.
Have you thought about blackout lining for curtains. If you have curtains which completely cover the window, then you can attach the blackout blinds (I got mine in Boyers). They work really well.
Have you thought about blackout lining for curtains. If you have curtains which completely cover the window, then you can attach the blackout blinds (I got mine in Boyers). They work really well.