Having house rewired - any tips / advice on how to integrate Smartthings (UK)

In terms of having the most options for the future with light switches, the two main recommendations are normally:

One) include a neutral at each switch box where you would like to have an automated switch. This will give you many more choices in terms of devices and protocols regardless of which home automation system you end up with. The reason for this is that most radiofrequency light switches use the neutral to power the radio so that it can hear the next “on” command from the network even if the light appears to be off.

However, lightwave RF and Lutron do not require a neutral, so they work well with retrofits. They are also very nice switches.

Note that neither lutron nor lightwave RF are directly compatible with smartthings. As you mentioned, some community members have found various workarounds requiring various degrees of technical proficiency and additional equipment, so there is some SmartThings integration possible, but not as much as you would get with some other protocols.

A receptacle will normally already have a neutral, this issue only applies to wall switch boxes where the neutral may be at the ceiling rose instead.

Two) have deep back boxes installed at each light switch and receptacle that you would like to automate. Again, this is just to give you as many options as possible, as it makes space for a radiofrequency device. If the switchbox is very shallow, then it limits the choices of devices that can be placed there unless you’re willing to put an extension collar which lifts the device above the wall. Or, as you mentioned, you can use a pocket socket plugged into a regular receptacle.

The following thread might also be of interest: