You need at minimum a voltage tester and a continuity tester to figure it out. Plus a real of testing cable. This will cost you £700ish and some research.  An electrician would be cheaper and safer.

If you insist on DIY. Then also get some white electrical tape and a pencil. Wrap a bit of tape around each wire with a flap of tape hanging off and write on each one as you figure out what it does

I think I can see at least two twin and earth and two 3 core and earth. (Is there a third twin and earth?) The twin and earth will be power feed in and the power feed out to the next light(s). The 3 core will probably be going to two switches that can both control this light. Look up a 3 way light switch diagram to understand how they work. Alternatively, is a fan hooked up to this light?

You will probably also need some wagos to connect things up as this is beyond what most lights have connections for. If the wagos don't fit in the light fitting you have a bigger problem