Plug kits here in the Colonies, range from cheap azz pos kits, to kits with blacksmith like tools, and more plugs than they could use in the Baja 1000, lol!

I have an m'cycle type kit for my scoots, and a 'heavier duty' version for the Vette. Doubtful that you can get the same brand over in AngleLand...
Here are a few I have/have used/have seen used/helped in using:
BlackJack Tire Repair | The Leading Manufacturer and Worldwide Distributor of Tire Repair Products the one I have in Vette

Nealey Tire Repair Kit - Repair Kits

All over the Amazon site, though most look like bicycle repair kits:
Amazon.com: Tire Repair Kits



Here's a list of 'stuff', but it is slightly to really overkill, imo:
Tech Tips


It isn't difficult, just not fun: get the tire rotated so the nail/object is right there in your face, extract the nail/object, ream the hole with reamer, dab of glue on plug, push the plug in with tool, let it sit awhile...pump the sumbitch up. Head down the road, and eventually find a tire joint to do a proper patch & plug or, buy a new tire.

Sound easy...a couple of times it was, on m'cycles, a couple of times it was not.

The Slime stuff is reportedly 'very improved' over the crap they sold a decade ago...
Dunno. YMMV.

M25: have driven it several times in rentals; fun outer ring road, esp in rush hour traffic, ;>)
GL, mD