Heres my two cents on uk soils and which ive tried,
homebase john innes no.1 seedling compost and john innes no.2 potting-on compost
Both of these soils are the same the only difference is the picture on the bag, both soils are full of sand and i mean full, after adding water it turns into cement and roots cant grow, ive tried adding perlite but it still turns hard and kills plants within a week.
Bio-bizz Allmix
Ive used this soil in the past and had no problems but the last bag I got was so strong it burns anything it touches, my ppm meter is maxed out reading the runoff 3.6EC or 1800 ppm runoff with ro water, unuseable. ive seen people using the light mix and its still way too hot with young plants burning away.
Plagron royality mix
Same as biobizz only stronger nothing can survive in this soil its so hot. and I think they even stopped selling it as nothing can grow in it.
Westland with added john innes multi purpose compost
This soil is hot and needs a flush before planting to avoid burning your plants, be warned the ph of this soil can drop very low causeing purple/red stems and then calcium/mag problems followed by death of plant, my water is ro water 0ppm 6.0 ph and i add calmag plus to 0.3EC, i can work this soil but i need to ph my water to 8.0ph and my runoff will be very low like 4.3ph and 2.4EC, i dient realize the ph was so low but now ive stopped the leaves dieing at least.
Miracle grow expand n grow peat free
strange soil puffs up 5 times in volume when water is added, unable to get any results from it my plants just sat and died i think its too hot and unsuitable.
All soils ive tried are very hot and I cant find any in homebase or b&q that wont burn of kill, I am now trying coco as theres more control of ph and ppm, if I were to use soil I think id go with the westland and add perlite and give it a good flush with a high ph water before planting.