Voipfone were previously great for me, £2/m line rental and a nominal fee to port the number in, but I was using them for business with a bunch of SNOM handsets, you may find something more residential/app based useful. Got to be honest, some of your 'wants' seem slightly questionable, you want to turn WPS off due to security concerns, but want completely open guest wifi and an emoji in the SSID. You realise anyone joins that and searches/downloads something questionable, and it's your front door that's going in at 5am, and you're being dragged out of bed and put in handcuffs, right? SIM deals I use are via Sky, £4 odd per month with unlimited calls/texts and more data than your average octogenarian knows what to do with.