D2 is def not to regs. Minimum of 300mm unbent pipe from the tundish before any bends.
One more voice to get a G3 plumber in to look.
Also, and seriously, you didn't answer the earlier question of whether you get it serviced.
It NEEDS to be done each year. Looking at the pressure reducing valve I see no evidence of the mech being removed in order to clean the strainer.
The fact is, if you have a leak on your HW system and end up claiming MANY insurers will now demand to see your maintenance history before even considering your claim. Remember all they want to do is make money NOT look after you. So, they look for every way out they can find...
I do notice however that both the pressure relief AND the temp & pressure relief valves have been changed. Shame the person never did any proper maintenance.