At the risk of stating the obvious, the type of hall is "Mission", and it is "they're" not "there", but the lyrics in the DT are a bit of a mess, so here's my tidy up.

MRS. ADLAM'S ANGELS
(Ralph McTell)

Sundays as a rule, us kids went to Sunday school
And Mrs. Adlam's said, angels stood by our bed
To keep us safe from dark, right through 'til days begun
We used to to lie awake, just to try and see one
And though we never saw one anywhere
We heard them softly sing in the air

Sundays occasionally, we were invited back for tea
And bread with jam and cream, made Sundays seem a dream
And in the dim Mission Hall, Mrs. Adlam playing
With Mrs. Adlam's angels everywhere
And we thought we saw a halo in her hair

Sundays for sure, aren't like that any more
It's getting hard for me, to see her face in front of me
I wonder if her angels have their arms around her curled
They're keeping her safe from harm,
Protecting her from the world
On a summer Sunday evening, do I dare
Hear Mrs. Adlam's angels in the air?

I think the above is pretty much correct, but McTell's diction is not always that distinct.

Alan