Sounds like a great plan guys
You actually have a lot of choices for hardy corals under metal halide lighting. Any soft coral would be a breeze in your tank. Yellow fiji leathers, other sacrophytons, mushrooms of any type, green nepthia, devils finger, xenia, kenya tree, spaghetti leather, star polyps, zooanthids, palythoas. They're all a breeze under any light, but in my experience really only yellow leathers, zooanthids/palythoas, and some mushrooms are really colorful.
For LPS, you could go with any brain coral type (open brain, favites brain, or standard encrusting brain) although I hear some open brain types are illegal in the UK
. You could also consider Any of the Euphylla genus corals (frogspawn, hammer, torch, galaxea) as they tend to be very colorful specemins (and often mistaken for anemone's
). BUbble corals are alo great LPS for beginners. I'd stay away from elegance corals, goniopora, blastomussa, echinophylla, or acanthestrea corals as all are very expensive and some are exceptionally difficult to keep. One word of caution with Euphylla or bubble corals, they are very aggressive species and should be kept away from other less aggressive corals, lest they start stinging. I still think they're some of the greatest corals though, so I keep them, just have to watch their placement.
And you guys even have the option of SPS with your halide lights. Some of the easier SPS corals include acropora millepora and pocillipora genus corals are generally easy to keep as well. Some montipora species are easy to keep, but maybe best reserved until after you get some experience under your belt