Great for seed sowing and potting up house plants. Available on the website and in-store. However my local branch (Wakefield) were out of Perlite and had only three bags of Vermiculite left.
£1.49 each (5 litres) or 2 bags for £2
from the website: "Holds many times its own weight in water to retain moisture close to the roots. Ideal for raising seeds and mixing with composts. Maximum Order Quantity 10"