Reddit mentions of SF Cable, 2ft EN50075 European 2 pin to C7 Power Cord

This isn't surprising.

> System76 products are compatible with world wide power grids. You may need to purchase a plug adapter for your computer.

This is saying that the charging brick is compatible worldwide, so you don't need to buy an expensive charging brick, but you still need to buy a cheap power cable or adapter.

You should be able to buy a cheap cable like this and plug it into the power brick. You should be able to find it at any computer hardware store. Or a simple adapter will do.

Are you using the duckhead plug, or the optional longer wall cord for the MBP charger?

I've compromised for travel with a wall cord that is smaller and lighter, and can probably be ...stolen... from some other device you already have. These replaced the little removable corner plug on the MacBook and iPad chargers.

https://www.amazon.com/Monoprice-107671-18AWG-Polarized-IEC-320-C7/dp/B009GUZ654/ref=sr_1_4?s=electronics&ie=UTF8&qid=1526315613&sr=1-4&keywords=c7+cable



This is the EU version - gives a bit more flexibility as far as plugin location, and is an adapter. Longer lengths are available, this one is 2 ft:
https://www.amazon.com/dp/B072R1FYXY/ref=gno_cart_title_0?_encoding=UTF8&psc=1&smid=A2LM6ZPY06LT1N


Maybe some shorter USB cables (one of these is USB-C, one USB-A) Either can replace both of your phone chargers:

https://www.amazon.com/gp/product/B06WWCRVZW/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B06XDB51VL/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

If you go the route someone suggested of charging phones from the laptop, smaller adapters like this may help:
https://www.amazon.com/gp/product/B076VP4P63/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

As for EU plugs, I like the tiny ones, but one of these provides two plugs in one outlet:
https://www.amazon.com/gp/product/B01NCZJ5UN/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

The charger can handle 240V fine (says on the back), so you don't need anything fancy. If you're nervous about the current power cord, you can always buy a Europe style cord or plug. They also make UK friendly versions.

I have both a Europe plug and a US plug (both right angle) for my camera battery charger. When I'm elsewhere, I just use one of them with a standard plug converter. For example, I use my US plug with a $5 travel adapter when in the UK.

Edit: noticed you're also in the UK. Added that content.