I had a look on www.rootsireland.ie/ & the marriage is there but has very little info!
John's address is Claushatoher which I've never heard of & can't find!
Date of Marriage:16-Feb-1836
Parish / District:BALLYGAR
Husband John Hughes Address:Claushatoher
I couldn't find any birth/baptism records for children of this couple on roots
IF they were RC, the R C registers are freely available at registers.nli.ie/. Type Ballygar in the parish search box & you'll get baptisms, marriages & deaths for Killeroran etc. It's hard work but might be worth a look.
Have you tried the Censuses? There are some Hughes in Galway in 1821 www.census.nationalarchives.ie/. No more Galway records in censuses until 1901 however!
You've done well to find what you have!