stuff growing under new shed, advice please

Hi I am in the process of building a shed. I have laid concrete blocks with shingle underneath to level and allow drainage ( I have read up on this and that was the way they recommended). The shed is 6m x 2.5m and along the length of the 6m the ground falls away to about 5" lower, so by using different size concrete blocks and that combined with the shingle and a bit of digging, eventually I got it all perfectly level. I also compacted the ground before laying that stuff.

It have worked on it on and off for a few weeks when I have time and constructed the base out of treated 4"x2" but now due to the weather and time, a lot of weeds, grass, etc has grown, do I need to do anything about this?

When I have finished, the underneath will be in total darkness as I will clad right down to the ground, and lay some sort of decorative shingle all round the outside ( this I also read, they say it looks good plus minimises the splashing back on to the shed when it rains preventing it rotting too quick).

I am guessing that nothing will live in total darkness and whats there will die. I do not see the need for a membrane and shingle because of this as there will just be a dark cavity underneath, can anyone advise me please?

put some Pathclear (weedkiller) down. It also prevents seeds germinating for several months unless you disturb the surface (it leaves a thin film of chemical)

if you have large tough plants, cut them off or treat with Glyphosate.

another thing I just thought of is rats etc getting under there, as I said I will put about a 12" band of shingle all round the shed and I will clad to the ground so really that should not be a problem, what do you think?

looks nice, but put in air vents