I've never been able to understand the "not recommended" advice given out by some "informed" sources.
In the electrical world, opinion seems to outnumber even the extensive range of official regulations on the subject.
It's perfectly acceptable under the regs to break into a 32Amp socket ring circuit and fit a fused spur for instance. (Containing a 13A fuse.)
From there, there is theoretically no limit to the number of other spurs that can be chained from the first.
The whole point, as others have said, is that the whole thing is covered by the single 13A fuse at the head of the line.
So, what's the difference with extension leads. None, except only that these leads tend to be pretty cheap and not terribly robust. Their connections are quite crude, but still fused.
More important, is that your whole system should be covered by at least one, but today, two RCDs. Fuses protect the wiring and outlets only. Your protection from earth faults (main shock protection) comes from RCDs.
As I said, they're pretty crude. Do think about having more proper sockets fitted right next to where you want them. There is no regulation limit to the number of sockets you can have............
Providing the total floor area of the circuit does not exceed 100 sq. metres............