What does it signify in the UK if a person is buried inside a church,
vs outside in the churchyard?

Obviously, there are fewer spots inside, and only the nobbiest of nobs 
can get a place there.  But is there an official qualification or 
something?   I know that in the UK, paupers were traditionally buried in 
unmarked graves; maybe that has something to do with it?

When I visited Westminster Abbey, most of the available floor and wall 
space was taken with memorial stones to the people buried within.  I 
think the qualification was... you had to be a hero to the British, or 
something...?

When I visited St Paul's crypt, there were a lot of worthies interred 
within, including Lord Nelson.  There was Wren's scale model of the 
church too.  Pretty impressive.   So what (even if it's just folklore
or belief) determines out vs. in, in church burials?   Anyone?   
Anyone?  Bueller?

Interesting question! It can't just be a question of 'worthiness'
because Winston Churchill is buried outside St Martin's Parish Church
in the tiny village of Bladon in Oxfordshire. If anyone deserves a
roof over his head, surely it is Winnie.

Money, money, money, surely is the answer to everything.

On this occasion, the qualification is not money, as Winnie's family
were not short of a bob or two. By contrast, among the worthies who
are buried in Westminster Abbey is Ben Johnson, the Elizabethan poet,
who died in 1637 in 'great poverty'.

According to one story, Johnson had begged 18 inches of ground in the
Abbey from Charles I but another story says that he had told the Dean
of Westminster that he was too poor to be buried in Poets' Corner and
that 2 feet by 2 feet would be sufficient for him.

So, evidently, all you have to do is ask, although you must obviously
ask the right person. However, asking a $2 question here is unlikely
to work.

If you've really set your heart on being buried there, I would suggest
that you contact someone really influential, like David Beckham. Or
Cherie Blair.

Oh, yes, and ideally you should die first. It can't be much fun being buried alive.

There's no single, simple answer, but clearly in former days, fame,
money and religious devotion would have been among the criteria. But
the wishes of the deceased and his/her family would also have been
crucial, which probably accounts for Winston Churchill's modest
resting place. (Incidentally, before interment, he had a state funeral
in St Paul's Cathedral.) Nowadays, I doubt if there are any burials
inside local churches; and even famous people, including Royals, tend
to be buried outside - see the first of the links below. Also, not
everybody memorialised inside a church or cathedral, eg in Poet's
Corner, is buried there - see the second link.

http://www.stgeorges-windsor.org/history/hist_burials.asp

http://www.westminster-abbey.org/tour/poet_corner.htm