Water Lily

I know 100% nothing about water lilies. So I have lot of really silly questions which I could probably look up myself. But where’s the fun in that ?   
How deep does the water need to be?
Can you get dwarf varieties?
Does the water need to be flowing at a reasonable rate?
Do the spread quickly/ are they thugs? 

I’m thinking a couple in the ditch at front of our plot. But it’s not very deep. Depending on the weather it’s a very general trickle to not quite a raging torrent. I’d like them to not take over and have their offspring disappear off down stream. 
Is this a possibility or Should I forget the idea?

I wouldn't do it.... they are thugs and take over a pond in seconds... my neighbour has a "wild one" that's huge. I have a small one and it's still can take over my pond in a summer from a small bit. It's also really heavy to pull out.

As usual I know nothing, but we've had two in our pond for years and they're still quit small and separate and haven't taken over. They need the sun to flower and don't like running water.

Plant them in a pot/bucket with holes in the side. Then you can take them out if they get too much. They get very tangled with dead slimy leaves in winter so benefit from a bit of pruning. I'm growing some in a plastic dog bed. No flowers yet but they were just tiny bits of root when I put them there last year.
Could you grow Marsh marigolds?
https://glenlivet-wildlife.co.uk/plants/marsh-marigold/

I’ve seen a few marsh marigolds around. I could transplant some of them.
After a little more research the water in our ditch isn’t deep enough for water lilies. Not even dwarf ones. Another random idea, binned 
We do have some floaty leaf thing in all the ditches around here. Really should get a photo and attempt to ID it. Never noticed any flowers on it .

I know 100% nothing about water lilies. So I have lot of really silly questions which I could probably look up myself. But where’s the fun in that ?   
How deep does the water need to be?
Can you get dwarf varieties?
Does the water need to be flowing at a reasonable rate?
Do the spread quickly/ are they thugs? 

I’m thinking a couple in the ditch at front of our plot. But it’s not very deep. Depending on the weather it’s a very general trickle to not quite a raging torrent. I’d like them to not take over and have their offspring disappear off down stream. 
Is this a possibility or Should I forget the idea?

I know you say your water isn't deep enough even for the small ones, but I thought I'd answer your questions still.
How deep does the water need to be? Anything from a foot down to two meters
Can you get dwarf varieties? Yes, and they're not as thuggish as the others. Try www.lincspplants.co.uk.
Does the water need to be flowing at a reasonable rate? No, they like it in ponds with still water, more than a flow.
Do the spread quickly/ are they thugs? Some are worse than others, but north-ways the cold in the winter knocks them back a bit, so shouldn't be too bad where you are

This is the stuff We’ve got growing in our ditch.

   


From a google image search (so not overly reliable)  I’m getting potamogeton distinctus A. Benn.  Hopefully someone can tell me that’s not what it is. Or it looks like we’ve got an foreign invader! 

Lots of forget-me-not at the other end of the ditch.  I’ve found lots of marsh marigolds in our little woodland at the top of the plot that I can transplant.

I don't recognise it - but don't know many water plants.
Does it have any flowers?
More on that Potty plant - https://gobotany.nativeplanttrust.org/sp...epihydrus/

It doesn’t have any flowers at the moment. Can’t say I’ve ever noticed flowers on it.
I’ve even less idea about water plants   .
I’ll have a proper read of that link. Definitely looks like it from some of images.

Found this. Panic over it’s everywhere
https://www.naturespot.org.uk/species/bog-pondweed