Hi everyone!
Firstly I want to say thanks so much for all your help with this, I feel not only that my tank is completely OK now, but also that I am much more equipped for the keeping of fish in general.
So, here is my update (because you were so helpful I thought maybe you would be interested).
I did a lot of research into the recommended fish and inverts here and decided on what I thought would be the most interesting and aestheticly pleasing in my tank. I rehomed the red-eyes and the dwarf gourami in my friends tank where they are having a pretty good time (at least, I like to think they are!). I kept the oto and got 2 more, so that's 3 otos. They've been eating cucumber and pellets of algae and are tubby and jolly looking! I then got a golden apple snail (which hasn't touched my plants at all!) which is a fascinating animal, I'm a big fan, and a bamboo shrimp. I installed an airstone to provide an uplift of water in one corner of the tank which the bamboo shrimp loves to stand in and feed. Again, a totally interesting animal! After a lot of research into tetra species I found that the black phantoms are peaceful, and like planted aquariums and have very similar requiremtns to the honey gourami (which they are peaceful enough to be with), as well as being comfortable in pairs and groups of 4, so I got 2 black phantoms and 1 honey gourami (wild type I thin, with the yellow dorsal and black ventral fins)!
I am pretty pleased with the tank now, the fish are all behaving very like normal. The black pahntoms (1 male, 1 female) are great in the evenings, the male displays and looks amazing and they seem to get on fine, there is no aggression and minimal chasing. The honey gourami bumbles around getting on with his business without being bothered and everything seems tip top! The plants have also settled down and grown up really nicely giving a little forest in the back 1/3 of the tank!
So once again, thanks to everyone for their help, I feel like I have happy fish now!