Best Price Square EXTENSION SOCKET 4 WAY BPSCA 2368 - PL11697 By PRO ELEC

Exactly, if you dont want your house to burn down dont cut corners with these products.
Do two things,

1 - Try to buy a reputable branded product when possible
2 - Look for extensions with surge protection, will protect your products and usually they are better made than none SP extensions. Specially important if you have an expensive phone charging or have a computer, TV, speakers powered from the outlet.

I use Belkin Surge Protector extensions personally. Depending on the product value connected they will cover up to £10,000 worth of connected equipment depending on the extension model and your requirements.

Of course you don't have to go fancy, but just don't buy a £2 extension for your own sake please!