Hi Ringy
What you have so far is your grandfather's birth reference and a potential marriage of his parents.
Births Jun 1922 Munger Dennis W Thompson Brentford 3a 361
Brentford registration district covers Chiswick and your grandfather's death registration states Dennis William and a birthdate of 29th March - so his birth was registered in the following June quarter probably in April.
I think you will need to obtain his parents marriage certificate to be able to research his mother since her name Thompson is a common surname unless you have any further information on her.
Marriages Mar 1920
Munger Arthur Thompson Kensington 1a 393
Thompson Annie Munger Kensington 1a 393
This is the only female Thompson and male Munger marriage
You can obtain the certificate from the GRO
http://www.gro.gov.uk/gro/content/certificates/Munger is a rarer name so much easier to follow.
This seems the likely candidate for your great grandfather
Births Sep 1898
MUNGER Arthur Brentford 3a 117
There are only three other Arthur Munger birth registrations between 1870 and 1910 and the other three all have middle names and are not registered in the London area. Obtaining Arthur's marriage details will confirm his father anyway but this is the 1901 census information for the Arthur born in 1898 in Chiswick.
1901 census RG13 1198 folio 54
39 Reckett Road Chiswick
Ebenezer Munger 42 Head Married General labourer Towersey Oxon
Charlotte Munger 36 Wife Married Wormley Herts
Edith Munger 12 Daughter Chiswick Middlesex
Emily Munger 10 Daughter Chiswick Middlesex
Frederick Munger 8 Son Chiswick Middlesex
Ellen Munger 7 Daughter Chiswick Middlesex
Daisy Munger 4 Daughter Chiswick Middlesex
Arthur Munger 3 Son Chiswick Middlesex
Albert Munger 1 Son Chiswick Middlesex
Because of copyright reasons you cannot request a search of the 1911 census, you will have to do the look up yourself.
http://www.1911census.co.uk/1891 census RG12 1033 folio 123
13 Quick Road Chiswick
Ebenezer Munger 31 Head Married Carman Thame Oxon
Charlotte Munger 27 Wife Married Wormley Herts
Edith Munger 1 Daughter Chiswick Middlesex
Lizzie Wicher 20 Visitor Wormley Herts
Marriages Dec 1885
Cooke Charlotte Eliza Edmonton 3a 374
MUNGER Ebenezer Edmonton 3a 374
The surname Munger is registered with the Guild of One Name Studies. Guild members research all lines for that surname so it might be worth contacting the Guild member to find out what sort of information they hold on your Munger line.
http://www.one-name.org/Regards
Valda