Personally I would not crimp solid conductors. To produce a correct cold weld involves several critical success factors; a crimp tool of the right type (single indent for fine stranded, circumferential impingement for stranded/solid); precise force applied consistently; correct crimp design for the conductor type (solid, stranded, fine stranded); crimp maker matched to tool maker (often forgotten).
Personally I would never solder. Most people can learn to solder with even a little practice (avoid a dry joint), and learn to bind two solid conductors together with fine copper wire so the solder does not take the current & fault current, and learn to adhesive heatshrink (preferably in the appropriate colours). However for extending a CU it is a bit messy.
I would always use DIN rail terminal block in a suitable enclosure. The CU uses such terminals, they are easy to access, inspect, maintain, alter, extend, reduce. Just bundle appropriate cables at entry to the enclosure with P-clips sized to hold the cables tight (so no load can be imposed on terminals), or route cables in trunking, etc.
You can get DIN rail terminals & enclosure from Ebay, CPC, Farnell, RS, Rapid, electrical factors, lots of places online. The box may cost about =A38, the DIN terminals and end-blocks will cost probably =A315-20 depending on number. If in doubt, post the circuits and it only takes someone a few minutes to suggest the part numbers required.
A novice might screw-up crimping or soldering, and right by a CU it is a cascading fire, whereas the probability of copying the photo with screw terminals is both safer and easier - it allows adjustment in future. Soldering & crimping does not (you end up running short of cable with changes, something a DIN terminal will prevent).