Gardeners Dream

https://www.gardenersdream.co.uk/gardenersdream-vermiculite-p2694

Vermiculite is the name of a group of hydrated laminar minerals (aluminium-iron magnesium silicates). Horticultural vermiculite is processed at high temperatures which produce flake-like particles that are completely non-toxic. Gardeners Dream offers this product in a large variety of sizes ranging from 0.5L up to 200L with free UK postage. 

This is the leading product in improving soil aeration.

Vitax

https://www.bhgsltd.co.uk/ProductGrp/horticultural-products/growing-media/compost-additives/vitax-vermiculite

Vermiculite can help promote faster, healthier plant growth and also possesses ‘cation exchange’ properties enabling it to hold and make available to growing plants ammonium, potassium, calcium and magnesium.

Providing good air balance, Vermiculite helps maintain an even temperature and can be used for seed germinations, pricking out, potting-on and plants in containers or tubs.

Crocus

https://www.crocus.co.uk/product/_/gro-sure-vermiculite/classid.2000034358/

Gro-Sure vermiculite is a naturally occurring non-toxic mineral heated to high temperatures to produce lightweight highly absorbent flakes. Retaining both water and nutrients, it releases them as required to encourage faster seed germination and establishment. Suitable for direct sowing of seeds of all sizes. Contains 10 litres.