I think your drying rack is cool and your plants look good.
The light thing sounds myth-y to me.
You may not need to flush for the full 2 weeks. I'd feed normally for the second to last week but do a heavy flush during the final week and then give only water with molasses if you wish up until you decide it is time to harvest.
Try hanging the buds to dry rather than using the rack, especially if your area is a bit on the humid side, as the UK is wont to be. The rack may be best suited to the smaller buds, but the big ones should be trimmed and hung. Keep air circulating no matter what you choose.