The English call dessert "pudding" so that can inform your choice. And, of course, the supper meal is "tea.'

Sticky Toffee Pudding! http://therunawayspoon.com/blog/2010/01/sticky-toffee-pudding/

Don't forget the sherry with the trifle. . . .must soak stale cake with sherry to revive. Creme Anglaise and fresh fruit . . very British, especially this time of year. Rice puddin' served hot with a large spoonful of raspberry jam on top. All childhood desserts!

Have to say, my favorite British dessert (though not technically a dessert - or 'pudding') is a wedge of good Stilton, with wheatmeal biscuits and maybe a pear or other fruit, served with a glass of port. The friends we stay with in London always serve this in lieu of a sweet...and I can't think of a better way - or less time-consuming prep - to end a meal.

I'm not sure if this is brilliant or gross, but when I lived in Scotland, people were always feeding me Snickers sandwiches after the bars. They're pretty delish:

2 pieces white bread
1/2 a snickers bar
salted butter

Cut the snickers bar into a few large chunks and place between two pieces of butter-slathered bread. Pop in your panini press/George Foreman grill and give it a few minutes to get browned on the outside and melty inside. Indulge.

I made this for the "wedding reception" when we watched the nuptials on "the Telly"

Fridge cake: see Recipe link below:

http://www.panfusine.com/2011/05/mcvities-orange-marmalade-fridge.html

Boulangere: you forgot the jelly! (or jello), Can't imagine Trifle without it!

Rhubarb fool.
Gently stew 1" pieces of rhubarb with sugar and vanilla.
When it is beginning to break down, cool and fold into softly whipped heavy cream so that veins of fruit are still visible. It looks prettier if you use pink rhubarb.
You can also use gooseberries. Or make an Eaton Mess the same way using crushed - uncooked - berries and broken pieces of meringue.

Do you have ingredients for a trifle: some stale cake, fresh fruit, whipped cream?