US visa after Iran visit
I can confirm that after visiting Iran UK nationals are denied the privilege of visa free travel to the USA, however a quick visit to the embassy will get you a B1/B2 10 year visa without any problems whatsoever. The embassy staff don't care that you have been to Iran, they just have to comply with the new law passed on down by their law makers. Entry into the USA is no different; in fact B1/B2 visa holders seem to be dealt with quicker than ESTA holders.