Preparing a plot where the soil is naturally very wet

Hi, this is my first post and I aim to become quite active here.. So I'm doing my first outgrow after a couple indoors, and I've found myself a nice plot and will be going to prep it very soon..

I have an issue, the soil seems naturally very wet - it hasn't rained in a few days the soil is still very black and moist, when you step on it your foot sinks slightly.
My idea is to dig out a hole atleast 1ft deep, and as wide as I need and fill it with a soil/compost mix which should be as natural as possible.. then I want to dig 1ft deep holes again after this has had time to set in which the ladies will go into themselves.

I'm doing autos and they will start indoors for 14 days before going out.

Any info, advice and tips you could give me would be great and really appreciated! Thanks in advance.

 

I will be amending my soil, what worries me is the current condition at the plot would likely cause root rot or drown the roots, it'd be extremely hard to not over water the ladies.

I thought if I dig up the entire plot area and put down my own natural as possible soil mix it may be better off? I know it's unnecessary and a lot of effort but I believe if you put in you get out.

What do you think I'm best doing?

 

I didn't think it was marshland, infact.. it isn't.. after digging into it and creating a big hole it ended up flooding with water some how. I'm guessing the mud is just so wet when I've removed most of it the water is remaining.
I will update with some pictures shortly, but am leaving it for a few days to see if it dries through before I go back.

If not it looks like i'll be filling buckets of mushy mud, creating an outer defense, putting a root protection sheet down, and filling it with my own soil.

 

After taking a few shovels worth of dirt out.. water forms from the dirt around the hole..


After preparing the rest of the plot... the dirt is all very wet

After lots of digging and lots of root removing...

Lots more digging.. more roots appear.. and more water forms seemingly out of nowhere


Last but not least.. after hours of work we seem to have developed a pond out of nowhere..


Now this is quite a large forest area, oddly the majority of it is quite wet ground but even more oddly there are no streams, lakes or anything like that.. it's a perfect spot and I don't want to be scared away by a challenge no matter how big it may seem.

 

Very surprisingly this is actually in England