The first smart devices you're generally going to want, beyond a smart speaker are smart plugs and bulbs. Smart plugs give you the ability to control otherwise dumb appliances and if paired with a smartphone can help you accomplish quite a few automations.
What can a smart plug do?
The functionality of each plug varies, some also have power monitoring and timer functionality built in, all smart plugs can be controlled remotely turning dumb applicances into smart ones. They let you have your eletric fire or heater turn on before you get home, control your kettle from bed or turn your TV with only your voice. Some plugs are only rated for 10A though meaning they won't handle your most power demanding appliances.
Exactly what plug you want to start with depends on what you're looking to do, we've hand picked some of the best on the market for you:
Power Monitoring Smart Plug
The Kasa Smart Plug by TP-Link is arguably the best smart plug on the market and it's not even £20. It's a Wi-Fi smart plug which means it doesn't need a smart hub, it monitors power usage meaning it can report on your power hogging devices, or be used to turn off a Washing Machine when it's finished. It's completely compatible with IFTTT, Amazon's Alexa and Google Assistant but sadly Apple HomeKit support has been cancelled. Despite it's bulky shape it works ok on a power block as you can fit smaller plugs on either side.
Value Pack Smart Plugs
Meross create an array of budget smart home appliances and these plugs are about the best price you can expect to get as they come in packs of 2. They're compatible with IFTTT, Amazon's Alexa and Google Assistant but there's no word as yet for Apple HomeKit support. The plugs are a little bulky, and the app is pretty basic but they work well and can handle virtually any device.
The Smart Strip
This Smart Power Strip with USB option allows you to control four devices individually, unfortunately USB ports are all or nothing. A cleaner looking, less bulky proposition than squeezing multiple smart plugs on to a powerblock, though not neccesary for most users. Functionality is pretty basic within the app requring your hub or speaker to take care of any automation. Given that it's a generic device 'AOFO' are not an established brand theres no guarantee as to how long security updates will be offered.
The Hive Smart Plug
The Hive smart plug is perhaps the sturdiest plugs on the market, it has an array of easy to define user settings and with its low factor frame it plays well on a power block, unfortunately it's not cheap. Still the plug offers an functionality such as timers and other automations within the app that you don't get with more generic plugs. It's part of the Hive set up which works well with IFTTT, Amazon Alexa, Google Assistant and Apple HomeKit support is expected this year.
The Security Geek Smart Plug
The Sonoff S26 Wireless Switch is a favourite among hardcore smart home fans, but more divisive for the average user. Reasonably cheap and with the perfect form for most powerblocks, however out of the box it's functionality is limited to telling it to turn on and off. The reason for this plugs popularity is it's ability to go cloudless, the popular Tasmota mod allows this plug to communicate with your smart hub inside your network over MQTT massively reducing any risk of the device being hacked.