B&Q Goodhome paint

Not used it. Personally Wouldn't consider an own brand paint. Dulux trade or crown is my preference

 

As above, learnt this lesson many years ago buy cheap buy twice.

 

As above. There are many good brands out there in addition to Dulux and Crown.

 

From my experience Magnolia emulsion is ok for covering same but some colored emulsions are complete rubbish with no covering power at all, I am thinking particularly of Valencia I am two coats on an existing orange wall already and it is still streaky, horrible stuff, never again!

 

I've used B&Q wall paints and found them OK quality.

Most recently I've used Andalusia Silk Emulsion which is quite neutral but a little bit warmer than magnolia:
GoodHome Walls & ceilings Andalusia Silk Emulsion paint, 2.5L | DIY at B&Q

I didn't have any covering problems but it was only over magnolia.