Roman Catholic records are difficult compared to Church of Ireland. I was born in the UK but live in Canada if you think I live in Ireland, unfortunately no. Unless you pay a genealogist you pretty much have to go there.
There is a online bmd for Galway. There are sparse records for Summerly's. It is divided into West and East. The record you get give you pretty complete information, if you email me directly firstname.lastname@example.org
I can give you the name, policy of rootsweb/ancestry don't allow me to use it and just remove the whole posting.
The National Library in Dublin has microfilm for RC to 1890 and after that records are in local custody and need to be searched in person. Each parish has its own records so my advice would be is to find the email address of the Parish and ask if you could see the registers, not all are forthcoming.Some are good, some not. I had a friend go two years ago and some of the clergy were not happy and in one case downright rude but they hadn't made appointments either. However, a graveyard has amazing amounts of information on 'some gravestones' of the inscriptions and in some cases a whole family tree.
The good thing about your family is you know the Parish already so you have a head start on most people.
I can't remember if I told you about the national archives 1911 census, www.nationalarchive.ie
has a goodly number
Summerly's and all but a couple were families.
The house address is there and I think if it still exists you might be able to see them on 'multimap' including a birds eye view which does circle around a house or area!! Its kind of fun. I don't know how much they have done in Ireland but the UK is certainly easy. I've seen where I grew up, my cousins house, etc.