40 UK gallons is what? 45 US gallons? Perhaps a little more? Anyway, it's not enough.
4x Dwarf Gouramis - These are quite peaceful fish but it's generaly difficult to get females so you're stuck with males - which are territorial and need around 10 gallons to establish a territory in or else you're likely to encounter some aggression. Also, these are fragile fish, very susceptible to disease, and don't do well with aggressive or highly competitive species.
2x Gold Gouramis and 2x Opaline Gouramis - These are the same species. There are several other color morphs as well. What they all have in common is one rather nasty disposition. Males, especialy, will even kill each other or their tankmates. They are not good fish to crowd and it's best to stick to a female-only group with no other gourami species if you want three-spots.
2x Pearl gouramis - Generaly peaceful, males are, none the less, territorial so should not be crowded. As is the case with most gouramies, they do better in trios (1 male, 2 females) or an all-female group.
2x Angelfish - You can't sex angels so most people buy a group of 6 or so and let them pair off, returning the 4 or so that remain after one pair has formed. Regardless, angels and all the gouramies you mentioned are all territorial and all occupy the same parts of the tank. There is no way you can combine 4 aggressive three-spots, 2 angels, 4 dwarfs and 2 pearls and not come across some very serious issues.
2x Clown Loach - Need a minnimum of 90 gallons realy - at least once full grown they do.
Basicaly, what you are proposing is not going to work. You should also cosndier that you'd be over-stocked as far as biological filtration is concerned.
If you want my opinion, get yourself some kind of smaller loach - eg: a group of zebra loaches. Add a trio of pearl gouramies. Plus put in a school of 7 or so praecox rainbows. Maybe, depending on how many of each fish you end up with, get a trio of swordtails and/or a pair of bolivian rams for some extra color. Try to balance out the tank so you have fish at all levels and a maximum of 5 gouramies of any type in total. Don't forget that angels and gouramies will only work if you are very careful of what you combine with what and only if you allow them plenty of extra room to set up territories.