I would like to grow House Leeks

You should be able to find bog standard Sempervivums, house leeks, in any garden centre.

i agree, i have them in mine..

If you want a selection of named ones then you need to go to a specialist nursery, but as said most garden centres have selctions of unnamed ones. If you live in Derbyshire then The Alpine Centre in Calver has about 600 varieties to choose from.