Can someone point me to a decent introduction to home automation options?
I've just bought a house. I'd like to set up some home automation, mostly heating and lighting, but even as a professional control systems engineer I'm finding the landscape daunting.
The house has a Hive boiler control and thermostat, though it seems the previous owner took the Hive Hub - he says on the advice of Hive. A new hub comes in at £70 and then it seems you need a monthly subscription (!) to make it work. My quick bit of research indicates the Hive components communicate by Zigbee, but I've found scant information on connecting to that network.
I also have a few some Hue light bulbs and a Hue hub. I like these, but control through the Hue app seems to be limited to the local network (though the scheduling is quite good). However, while they're good in lamps, as room lights they leave a lot to be desired - principally because if anyone turns the room light switch off, they stop working. It seems the Hue Hub has an HTTP (and HTTPS in beta) interface which can be controlled with Google Home or Alexa, though I don't own either of these devices yet.
Instead of the Hue bulbs, I'd like to replace the room light switches with remotely controllable versions. The £15 off Amazon or eBay is the Sonoff T1, which as far as I can make out has both a 433MHz radio and an ESP8285 WiFi chip. There are plenty of GitHub repositories with custom firmware for this switch, but as far as I can tell no documentation on the default WiFi control that would allow you to link it in to anything else. Also, it requires a neutral feed to the switch which my house doesn't have (at least not the couple of switches I've checked). I'm in the UK, so legally I can replace existing switches but not rewire.
Other fixed wall switches seem to come in a variety of WiFi, Zigbee and 433MHz versions and again, documentation is somewhat minimal. There are versions that don't require a neutral line, but these seem to be rather more expensive (and would they trip an RCD?).
If I go with WiFi enabled devices, then at least there's no need for masses of hub devices kicking around. As it is, I already (apparently) need a Hive Hub and a Hue Hub to communicate with the boiler and the Philips bulbs, and pretty soon I'm going to run out of router ports.
So. Can someone point me to a comprehensive overview and some recommendations on how to go forward? What are the up.downsides to 433MHz, Zigbee and WiFi control? Is it feasible to replace the Hue and Hive hubs with a Raspberry Pi and some sort of hat? Are there economical options for no-neutral-feed WiFi dimmer switches? Is it feasible to roll my own control system for this with a Raspberry Pi or similar, or will I need to join up to the Google Home or Amazon Alexa bandwagon to do fancy scheduling and remote control?
Thanks for any help!