It may sound odd, but because of the cost of an individual device radio, the least expensive option (if you’re going to have smart bulbs that are always receiving current anyway)i is often a Wi-Fi mobile phone with no contract. I don’t know what these cost in the UK: in the US one can buy them for less than €15. And they can replace multiple switches in some cases.
These are typically used with SmartTiles, A dashboard app that can be customized to show just the devices that you want. It does work for UK customers and is very popular. It works in any web browser, so it can work on most smartphones.
There is also a forum topic where people share ideas and photos of the hardware they’ve used with these dashboards:
As I mentioned, a somewhat unconventional approach, but can be much less expensive than the other options and gives you a lot of flexibility.
Considering all circumstances
The caveat with this approach is that if your Internet goes down, the telephone will not be able to control the bulbs at all. At my house, we keep the original switches in place but covered with a child safety lock to remind people not to use them. Then we use other methods for daily light control. If the Internet or the home automation system becomes unavailable, we still have the original switches as a fallback. So it’s just a matter of thinking through what you would want to have happen if the Internet were unavailable.
Other possibilities
As far as other possible devices, including remotes, see option two in the UK lighting controls FAQ.