If defence costs are to be cut to the minimum then the MoD must cease overseas operations carried out for international political advantage and return to its primary role - the defence of the nation. The primary requirements of securing our airspace, our coastline and our lines of supply dictate that we require primarily, a Navy and an Air Defence Force. Indeed, those are the two armed forces that kept the British homeland secure in 1940.
As an island nation, an army is only required in the event that the primary roles fail and invaders set foot upon our shores. In which case Winston Churchill's postulate comes into force.
"We shall fight them on the beaches etc., ....... we shall never give in."
The army are primarily a force of last resort and in the last resort everybody is a soldier in Dad's Army. Which is why Britain has never in its entire history officially had a "Standing Army". Its worth remembering that our rifle clubs and Bisley Camp itself are a remnant of the old County Volunteers that morphed into the Territorial Army.
So in answer to the question, even though I ceased to serve in Britain's finest a long time ago, if I'd been obliged to make a choice of Navy, Army or Civvy Street, I didn't join the Royal Air Force by accident and my choice would have been option 3.
If we were ever under threat of invasion, I can still shoot a 'Possible' at 600 yards and I'd march (or at east totter along) with Dad's Army.