The tank has all settled now and the water was so very clear it was wonderful. I made the mistake of adding a couple of indian almond leaves and the tank looks healthy enough but it isn't as easy to see into it so I think I won't use Indian Almond leaves in this tank from here on and it should slowly get back to crystal clear water.
I attach some pictures taken by friends so you can see there are some red cherry shrimps in the tank, the pictures arent the best quality unfortunately! I like the tank design as it looks very tidy. The heater is a bit iffy and I have reset it twice when the water temperature dropped, but the aquarium is easily seen from where I normally sit (and you can see the stick-on thermometer in the photo) so it is easy to keep an eye on it for now.
I am keeping a chair next to the tank so that hopefully I can do a better job of keeping on top of removing the poor quality/colour shrimp regularly, so hopefully I can avoid the 'over-run with wild type' that happened before.
The design of the tank means there is only the one plug for the light AND filter, very tidy, but does mean you can't use a timer for the lights (???). I did know it was like this before I bought it but was/am using 2 of my usual cheapo filter sponges anyway so it isn't a problem. Here is link to tank just in case anyone UK based is interested;
https://www.petsathome.com/shop/en/pets/love-fish-panorama-aquarium-black-40-litre
All the 8 neon tetra and 5 ember tetra are still alive and looking as happy as fish can look(?), and there are a few assassin snails, so I think it is pretty well fully stocked for now? I don't like the floating weed but that is in there as friend takes some each time they come, so I just grow it for them, but I may just stop doing that as it just gets in the way when trying to catch cull shrimps! I MAY try some water lettuce from one of the other tanks, but that tank has a duck weed problem, so I am a bit hesitant as I don't want to also transfer that problem at the same time?
I think that is about it, but ask away if you have any questions.