Simie,
Brew a easy beer with the same yeast that you want to use for a starter. Give it oxygen and nutrients for a healthy ferment. This will be starter you need for the English bitter. Two weeks later brew the English bitter let it cool and then siphon the easy beer off the yeast cake, (bottle) and dump the English bitter wort on the yeast cake from the easy beer. It will ferment within hours. Two beers one batch of yeast. Good luck
