Reddit mentions of Brother Mobile TZEFX651 Hge/Hg/Tze/Tz Tape, 0.94" W x 26.2' L, Black Ink on Yellow Label

First and foremost, nylon zip-ties, along with a tool to tighten and cut them:

https://www.amazon.co.uk/s/ref=nb_sb_noss_2/261-5150240-1396533?url=search-alias%3Daps&field-keywords=cable+tie+tools

You can get adhesive clips to tie cables under a desk:

https://www.amazon.co.uk/Adjustable-Cable-Clips-Adhesive-Clamps/dp/B01LYO307S/ref=sr_1_6/261-5150240-1396533?ie=UTF8&qid=1540176501&sr=8-6&keywords=cable+clip+adhesive

These 3M Command brand ones are designed to be removed without marring the surface they're stuck on:

https://www.amazon.co.uk/Command-17302CLR-Small-Clips-Strips/dp/B0084M696K/ref=sr_1_2/260-9985987-3740648?ie=UTF8&qid=1540177482&sr=8-2&keywords=3m+command+cable+clips

These Velcro brand cable ties on a roll are cheaper and more convenient than the fancier kinds with tabs:

https://www.amazon.co.uk/VELCRO-Brand-One-Wrap-Reusable-Ties/dp/B00186QF2C/ref=sr_1_8/261-9295406-7442635?ie=UTF8&qid=1540176024&sr=8-8&keywords=cable+ties+velcro

If you want to bundle together cables in a sheath, these ones with zippers work better than velcro ones:

https://www.amazon.co.uk/Management-JOTO-Computer-Entertainment-Organizer/dp/B015HWXG4M/ref=sr_1_7/261-9295406-7442635?s=diy&ie=UTF8&qid=1540176119&sr=1-7&keywords=cable+zipper

(word or warning: the zippers are not exactly premium YKK or RiRi quality, be careful when engaging them to avoid cross-threading..

For routing cables, these Danish organizers are pretty sweet (not available on Amazon.co.uk for some reason):

https://www.amazon.de/s/ref=nb_sb_noss_2/258-3647476-1208213?__mk_de_DE=ÅMÅŽÕÑ&url=search-alias%3Daps&field-keywords=cablox

Generally speaking, it pays to replace power cords, Ethernet cords and the like with shorter versions to avoid having slack cable turn into spaghetti. In the UK, your plugs are so bulky a splitter cable like these makes sense:

https://www.amazon.co.uk/s/ref=nb_sb_noss/258-6762083-9871312?url=search-alias%3Daps&field-keywords=IEC+power+cord+uk+plug+dual&rh=i%3Aaps%2Ck%3AIEC+power+cord+uk+plug+dual

Finally don't forget to label your cables. This Brother flexible tape works in some of their label makers (you need either a PC-connectable one or one that has software to print labels that can be wrapped around the cable):

https://www.amazon.co.uk/Brother-TZEFX651-TZEFX-651-BLACK-YELLOW/dp/B00WFOQERC/ref=sr_1_4/261-5989537-8091249?ie=UTF8&qid=1540177234&sr=8-4&keywords=TZe-FX651

here is a shot of it in action:

https://majid.info/images/FullSizeRender.jpg

They also have some label makers that will print on heat-shrink tube labels, but obviously that will not work on ready-made patch cables.