Block bbc.co.uk/iplayer domain in router.
How to still avoid £145 fee.
Log in to your router and block the domain bbc.co.uk/iplayer, remove iOS / Android BBC iPlayer Apps from ALL devices, as these don't directly use the domain bbc.co.uk/iplayer. I also removed BBC 'iPlayer' Radio, which is the only thing that bothered me. (some say you don't need to, but probably best to be safe than sorry, the key is in its name)
My biggest problem with the legislation change is I have have not had a TV for more than 10 years, I would accept paying a Netflix £5.99 a month fee to watch iPlayer only, but this change its all or nothing. I don't want a TV in my house because its such a waste of time, I just don't want full blown TV ever again, I've really not missed it, so it ended up as nothing.
My ISP could theoretically prove I have never streamed from bbc.co.uk/iplayer, so if it went to court that would be my evidence, blocking iPlayer in the Netgear router stops anyone accessing it, by mistake.
Then of course, you need to write to the before tomorrow -1st September 2016, describing what steps you have taken, how you understand the change in legislation, how this effects things.
Sounds a pain in the neck, but its easy enough, to jump through their hoops, but don't do this if you think you might try and watch iPlayer at some point, its just not worth it, easier to pay up.