Why can't i find Worcester Permain apples, they are better than Cox.

You could grow your own Catkin -Worcester Pearmain Apple Tree (Malus domestica 'Worcester Pearmain') Available on a M.27 Very Dwarf Rootstock and supplied in a 12 litre containers.
Or you can but the apples from various suppliers:
Orange Pippin Shop
York, Yorkshire.
Keepers Nursery
Maidstone, Kent
This web site will help
http://www.orangepippin.com/suppliers.aspx

You could also try Waitrose - I believe they sell

Lewisham se6

Are you SURE you want to grow Worcester Pearmain? It may be OK straight off the tree, but the fruit goes soft very quickly once picked.
For early apples, try Discovery, which is crisp and juicy and makes wonderful apple juice. For alternatives to Cox, try Sunset, Jupiter......etc (Keeper's Nursery is brilliant for finding apples to suit your requirements). Make sure you select trees that will be pollinated by other varieties in the same pollination group. Jupiter needs TWO pollinators.