you might be able to get frames on trial (without prescription lenses), then order if you like them before the code expires.
but they do have a policy of return the glasses for a refund for whatever reason.
or you should try out their frames every so often, and wait for the code to appear again.

I've bought from this company before, got prescription sunglasses and regular and have bought both with and without coatings and I've seen no difference. Unless you plan on dropping them or being in an environment that hazardous I wouldn't recommend the coating. :sunglasses:

I've had glasses from glasses direct with and without the coating and I've noticed a decent improvement on reducing reflection/glare from using on PC/driving with the coating.