The angels are probably hanging on the right side of the tank because there is more space vertically. lol They will grow to big really for your tank. They are more suited to the taller 20" tanks once they grow up.
For cheapness I would just go to Pets at home and buy 3 Tropica potted plants for £9 or whatever the deal price is. Tropica is the brandname of the fert people are suggesting above Topica Plant Nutrition +. It is quite important you buy the potted rather than the rubbish in the terracotta pots. Tropica are in black plastic pots and you get loads of good quality for your money.
They will have a label much like you get pushed into the soil of a potted garden plant to tell you what light they like, how tall they grow etc but as a guideline you should go for Ludwigia species, Hygropylia species, Rotal Species (but not macrandra) Cryptocorynes etc. Get them home and seperate them carefully. 3 pots will be able to be spread over the whole substrate and create a decent planted tank that you can eventually move some out to sell and replace to get more variety in there.
I hope the ceramic diffusor works for you. every week take it out, put some bleach on the disc for 5 mins then rinse under the tap, then put bleach on the disc for 5 mins again and rinse. Then put a little water and a little dechlor on the disc for 10 minutes and it should stay clean and perform well. I tend to take the sucker off the wall of the tank and stick the diffusor on the tiles in the kitchen for each 5/10 minute spell. lol. be careful when removing replacing it. hold the pipe and not the bowl or the joint or it will break especially with the smaller ones.
The highest wattage light you can get for T8 (1") for a 18" long fixture is 15W. I would just get an Arcadia Freshwater (known in P@H as Classic daylight or something similar. has a green box) and get an 18W Arcadia reflector. tube should be £11ish and the reflector £5ish. Don't get more light until you know it doesn't work or you want to have a faster growing tank!!!.
Personally I would get rid of the blue ram and get another male bolivian. Blues are not as hardy as bolivians and they dont have the character either of the bolivians. The reason the bolivian male was attacking the Angels was that you shouldn't really have the angels in with other Cichlids in a tank that size. You have some decisions to make. The angels will grow too tall for the tank you have. You have 3 species of Cichlids in the same tank. Therefore you either need a taller tank for the angels or a larger tank to keep all of them or find a new home for the angels and decide on blues or bolivians.
These are what I would choose:
This is my dominant male and female with the 'beta' female in the background. I have 2 male and 2 female bolivians in my 33USG and yes they bicker and chase every now and again but that is what they do. They have a pecking order which they try to maintain and they have territories which they defend especially when spawning which they do monthly (before plecs and cardinal tetras sneak in for feeds.) It is good to see this behaviour rather than 1 of this and 1 of that. Try to keep shoals of fish and you se much more natural behaviour from them. My tank is about the lower limit for 2 pairs. yours would fit 1 pair but you may find they pair up and spwan for you. I also have 4 pitbull plecs who play together etc. they are great and only 3inches fully grown. then I have 3 Otos who follow each other aroud the tank and 20 Cardinal Tetras that schoal around the tank together. It all works because of the plants, rocks and wood. They give territory markers to the bolivians. the pitbuls like the wood to munch on. The cardinals like to swim though the plants and the Otos keep the plants clean. The pitbulls enjoy cleaning up the bloodworm that the Rams and Tetras leave etc. Everyone in there compliment each other because the tetras and rams provide a lot of entertainment. the pitbulls do too but they are also scavengers and clean up any left overs as well as munch the wood and glass clean. Otos are the least visible inthe tank but keep the leaves and glass clean too.
And no they don't take away from the effect of the tank. Most of the pics I take of my tank for my journals you can't realy see the fish (look at sig pics) and these are not picked out because of that. I take a few pictures and the one that has the best focus gets the nod.
Good luck
Andy
I dose the tank once a week with Nutrafin plant grow, which is not that great, so ill soon change the liquid food (any ideas?).
What i may do is take my bolivian ram to maidenhead acuatics and see if i can swap and get a male german blue ram. The bolivian is starting to chase my angels which i don't like. even though the ram is stunning 
they are only around 2 cm's.
