The source I found for the British infantry section was contained in The Candian Army Journal Volume 13.3 2010. An article by Major V. Sattler, CD, and Captain M. O'Leary, CD entitled "ORGANIZING MODERN INFANTRY: AN ANALYSIS OF SECTION FIGHTING POWER".
This document is a review of 21st century section firepower and organisation.
In the document it has a paragraph detailing the differences between normal British Army organisation and that used in Afghanistan.
"Of particular note is that, as a result of combat operations in Afghanistan (Op HERRICK), the British Army's actual arming of the section is markedly different. The section commander and 2IC are armed with SA 80A2 5.56 mm rifle. There are two light machine-guns (similar to Canada's C9), two under slung grenade launchers (M203 equivalents), one general purpose machine-gun (same weapon as Canada's C6), and one sharp shooter with a L129A1 7.62 mm assault rifle (procured as an immediate operational requirement for the operation). The SA80 A2 light support weapon, which has a heavier and longer barrel allowing greater muzzle velocity and accuracy than the standard SA80, is still in inventory but is not used in theatre or domestically."
PDF link
With regard to the issue of the combat shotgun I looked at the MOD site which says "The combat shotgun is for use by the Point Man of a section at close quarters within close country and complex terrain. It allows the soldier to apply a quick rapid rate of fire over a large area using a variety of ammunition natures." this would indicate one issued per section rather than one per fire team.
link
Resulting in the following organisation:
Charlie Fire-team:
• Corporal
armed with an L85A2 5.56mm rifle.
• Rifleman
armed with an L85A2 5.56mm rifle with 40mm underslung grenade launcher and combat shotgun.
• Rifleman
armed with an L110A1 5.56mm light machine gun.
• Designated Marksman
armed with an L129A1 weapon.
Delta Fire-team:
• Lance Corporal
armed with an L85A2 5.56mm rifle.
• Rifleman
armed with an L85A2 5.56mm rifle with 40mm underslung grenade launcher.
• Rifleman
armed with an L110A1 5.56mm light machine gun.
• Rifleman
armed with an GPMG.
With regard to the IED values from the copy of the rules in front of me a Mastiff had an IED value of 5 and a Warrior one of 9 which given reports in the media seems contrary to how the vehicles actually perform.
Hope that helps, best wishes
DJ