id like to use proper lights as opposed to low voltage stuff.
Since 230 vac is low voltage not sure what you mean? The proper lamps use transformers wired with the primary in series the idea being the same current will go through each transformer however long the run is so each lamp will be the same brightness. This is the way to light mile long drives or runways which I am sure is not required.
So I would assume you there for want extra low voltage which instead of using a transformer in series use voltage droppers in parallel which use a switch mode method to adjust the voltage to compensate for volt drop.
To be frank at 8 meters neither method is required and by using low voltage (230 vac) LED lamps these have a built in compensation anyway.
Heat is the biggest problem with lights outside. Unless left on 24/7 each time they are switched off they will suck in any moisture as the air inside cools and contracts so the cooler the lamp the better and also don't leave any air filled voids even if only filled with petroleum jelly it will reduce the amount of water drawn in.
With LED the wattage required is low so you can have the voltage dropper in the dry with a relatively long extra low voltage supply clearly running along the drive line you will know where the cable runs and it will not be in much danger from the spade so can use cheaper cable than would be required with low voltage. With LED also DC so RF from cable is not a problem.
There is now a provision for electricians to sign off other peoples work in the building regulations but this has not been taken up by the major scheme providers neither is it endorsed by the IET/BSi regulations which require the person who is responsible signs for design, installation and inspection and testing.
So if you want it done following regulations then step one is get an electrician who then can supervise the work telling you what you should do and where he feels it's appropriate doing those bits himself. As he is in control he can then sign. However I know my son agreed to do this once and it caused him such a problem with broken promises specially on when something would be done ready for next stage he decided never again. Unfortunately this is common so finding an electrician who will supervise the work is rather hard.
So likely best option is extra low voltage if you want to DIY. In the main the extra low voltage or low voltage selection is as much to do with the market and often the best looking lamps for your drive will only be available in either or not both so may be better to select the lamps you want first then return to installation method.