There's no location shown for where you are...but you're checking a UK website, so I'll assume that's where you are. I don't know anything about that company, but some kits sold here in the US have things in them that many people won't need/use for DIY the way they prefer to do it.
You can usually do alittle research, to see what most real people who DIY actually use...and then order just
those things yourself. A company who puts together a "kit" for DIY...would love to have you
buy as much as possible, naturally. They don't care if you'll personally use it all or not. Once you've bought it...it's yours!
There are Blogs to read here on the ECF, many many discussions about DIY & supplies used for it, "stickies" posted at the tops of
threads and boards regarding it, etc.
I'd check out a bunch of those, and then decide which way to go.