Sorry mate, I'm with these guys, i bend the rules in this hobby and i have a 180l jewel vision so not much difference in size volume wise and i have more swimming length. a yellow tang is a definite no. sorry bud.
just think if you get one, it dies and wipes your tank out it could cost you £100's which you could have put towards a bigger tank. i went with a kole tang (which is the most suitable) and it was never "happy" it would have survived but thats not fish keeping. get yourself a dwarf angel. maybe a lemon peel. they're pretty and quirky and if you're keeping softies as coral I'm sure you will be OK.
One thing i want you to realise is although you may get the tang small it will suffer from stunted growth, may deform its spine and will rapidly reduce its life span. as it gets bigger it will become more aggressive to all the other fish and will be very agitated. Just think if you started of having the whole of the UK to roam about in and then i confined you to a house. That would be stressful enough. you're now wanting to confine it to a cupboard.
please look at bicolour angels, lemon peel angels, coral beauty, flame angel. Much more suited. Still pushing the rules a little but I'm sure they will be fine as long as you keep on top of water quality.