Wow, first let me say you're in England? LUCKY....I would kill to live in England or Ireland or Scotland - those three have THE cutiest accents and Ireland is the home of Thomas Andrews Jr....My hero anyway back to your issue.
Have you thought of applying for a O1 Visa? It allows actors from the U.K. and other countries to come to the U.S. and work and it's not expensive, a lot of actors have done it, I'm sure - Gerard Butler, Ewan Stewart, The guy who played in The Artist - can't think of his name. Getting to the US and getting work would be great because you'd really get access to roles and such.
The question I have is, were you born in the UK or do you just live there thus - in England's eyes you're considered a foreigner?
"entertainment" visas are not for every actor/entertainer. You have to be established/known actor with representation in your country to be qualified for Entertainment visa.