The listing you have linked to is misleading. It doesn't directly take grid modules at all. It takes a "double" sized accessory.
Be aware that Scholmore click have three different modular systems. "Minigrid", "GridPro" and "New media".
"Minigrid" and "Gridpro" are click-specific, and the ranges do not include 13A sockets.
"New-media" are "standard"* "Euro modules", and the new media range does include 13A sockets (as well as several other types).
Unfortunately, a 13A socket, two switches and a fuse adds up to 5 modules, and a Euro module double plate only accepts four modules.
So basically if you want to build a combined socket and FCU out of Euro modules and fit it on a "double" plate you have to give up switching on either the socket or the FCU.
What you really want IMO is an enclosure designed to accomodate two single accessories. Unfortunately few manufactuers seem to make those, I did find one but it's light grey.
https://www.electricals247.co.uk/enterna-outdoor-enclosure-box-2-x-1-gang-dual-waterproof-35178/
*If anyone can actually find a standard for the bloody things do let me know.