I'm really glad that I've found your group here because I'm doing my PhD at the moment at UWE in Bristol (looking at Holocene sea-level change in the Somerset Levels) and have come across some diatoms in my sediment cores that are really hard to identify. I'm planning to post up a couple of pictures in the coming months in the hope that someone might be able to give me some hints as to how to start identifying them. They will mainly be brackish (marine brackish to freshwater brackish) species. I'm more than happy to help people identify other things as well. I hope we might have some interesting discussions.
All the best