Suggestions for new 205g (uk) build??

[Dreadz]

Have a 66x36x24 tank lined up and am trying to decide what to do with it. Really want to set up a discus tank but with my tap water testing at pH 8-8.2 am wondering whether I'd be better off choosing fish to suit my water rather than having my first foray into RO water set ups on such a big scale, which if I do mess up will likely result in the loss of a lot of expensive fish!!
Suggestions or advice readily welcomed. Thanks.

 

[...joey...]

Out of all the fish I've kept my favourite four are: 1.discus 2.african bush fish (small pred witch will not ever bother any other fish except the smaller species of tetra) 3.decorated squeeking catfish (hide a lot but really nice looking fish) 4. Hujeta garr (also small pred really cool to watch eat and look at) check them out on YouTube. I live in the south of uk our water down here is off the scale hard bit I'm in the middle of changing to RO water for my discus I've had them in hard water for months and they have been fine with no extra effort but I'm doing the RO simply to bring out the last bits of their colours. Hope I helped