[Simon Waters (OP)]

Silly question, but my degree was theoretical physics and obviously I didn't do enough lab time.

The science museum in London has (use to have?) a fantastic Cloud Chamber. Large clear plastic table like structure (with a regular hum of some sort of pump).

It stuck in my mind as the kind of thing which would make a great dinner party table if you could keep the noise down.

Searching around no one seems to sell Cloud Chambers, so I assume either the suppliers keep a low profile, or everyone makes their own.

Various folk and science journal have instructions and tips, most involving dry ice, and other stuff you probably wouldn't want under a dinning table, or too close to nosy children. The science museum seems to have made a very accessible cloud chamber suitable for public display.

If I wanted a relatively quiet and child friendly cloud chamber, ideally on the scale of a dinning table, where would I start? Would these criteria compromise the science in the type of particles you could see.

[Jolly- Joliver]

Interesting idea a cloud chamber dinner table.

I assume you would like space for your legs, sounds like a table shape made of glass, or a fish tank in the shape of a table being used as a cloud chamber.

I think the chemisty would probably be best done in the leg areas.

Probably would entertain children, and might tell you if the house went radioactive, bonus. 

[Bored chemist]

"I think the chemisty would probably be best done in the leg areas."
What chemistry?
Anyway, it's possible to build your own  cloud chamber and you can use a Peltier cooler aray rather than dry ice.
Unfortunately I suspect the answer to "If I wanted a relatively quiet and child friendly cloud chamber, ideally on the scale of a dinning table, where would I start? " might be that you would start by winning the lottery.

On a smaller scale, it's quite possible
http://www.instructables.com/id/Make-a-Cloud-Chamber-using-Peltier-Coolers/

[Jolly- Joliver]

"I think the chemisty would probably be best done in the leg areas."
What chemistry?

The ironising of alcohol, or use of dry ice, you know the chemical interactions that produces the clouds

Anyway, it's possible to build your own  cloud chamber and you can use a Peltier cooler aray rather than dry ice.
Unfortunately I suspect the answer to "If I wanted a relatively quiet and child friendly cloud chamber, ideally on the scale of a dinning table, where would I start? " might be that you would start by winning the lottery.

On a smaller scale, it's quite possible
http://www.instructables.com/id/Make-a-Cloud-Chamber-using-Peltier-Coolers/

Does it have to be so expensive? I mean finding a secound hand glass table top, then using sealed double-glazing underneath it, You could make a minature tank say an inch space, for the cloud chamber than runs the whole length of the table.

Cutting holes for the legs, in the lower glass. If all four legs were active with the alcohol iodising going on inside them, should fill up the whole table space should it?

Kinda like

 [______________________________]glass top- magnifying Clouds below
 |{  double glasing pane          }|- sealing material
 |{  interior space for clouds    }|
 |{ double glasing pane | |       }|  | |whole in lower pane
     {  }-leg               {\|/} - leg             \|/ stuff going in hole       
                             { & }           & - production factory of stuff to go in hole
                o
               /|\- Little jonny
               / \