Am I missing anything obvious for a build?

Hi All,

I'm looking at building my first desktop and want to run MacOS, Windows and Linux. I've been on TonyMac and tried to work out my potential build and the cost. So far I've got:

Y - GIGABYTE H270N-WIFI - £116.83 - https://www.amazon.co.uk/dp/B01N4IEJN0/ref=as_li_ss_tl?ie=UTF8&tag=tonymacx86-21

Y - Intel Core i5-7500 3.40 - £157.00 - https://www.amazon.co.uk/dp/B01MZZJ1P0/ref=as_li_ss_tl?ie=UTF8&tag=tonymacx86-21

Y - GTX 1050 - £117.42 - https://www.amazon.co.uk/Gigabyte-Nvidia-1050-GDDR5-PCI/dp/B01MG1MP73/ref=sr_1_1?s=computers&ie=UTF8&qid=1509904118&sr=1-1&keywords=gtx%2B1050&th=1

Y - Crucial 8GB DDR4 - £80.51 - https://www.amazon.co.uk/dp/B00MMLUYVU/ref=as_li_ss_tl?ie=UTF8&tag=tonymacx86-21

N - Corsair CP-9020097 - £40.97 - https://www.amazon.co.uk/Corsair-CP-9020097-UK-PLUS-Power-Supply/dp/B00TE4XSMA/ref=sr_1_1?ie=UTF8&qid=1509908457&sr=8-1&keywords=550W

? - Phanteks P400 - £63.99 - https://www.amazon.co.uk/PHANTEKS-PH-EC416P_BK-Eclipse-Midtower-Window/dp/B01BLHP4RO/ref=sr_1_1?ie=UTF8&qid=1509908700&sr=8-1&keywords=phanteks+p400

= £576.72

I already have an SSD, monitor, keyboard, mouse, an ethernet connection and the Phanteks case says it includes 2 fans so I assume I don't need another. Based on that information would there be anything else I need to purchase?

The other Hack specific question is to do with the power supply, the one I've listed isn't on the recommended site however I assume it shouldn't have any incompatibility, is this right?

Help is hugely appreciated!

Thanks!