The 1841 and 1851 records contain only a very small percentage of of the population, and if Hugh and Bridget emigrated in the 1830s, they definitely wouldn't be there. However, Tuam parish records have been filmed back to 1790, so you should find them there if they were from Tuam. If it's not feasible for you to go to a Family History Center and read the film yourself, you could ask the Galway East Heritage Center to look for the baptism of Thomas in 1827 and the marriage of Bridget and Hugh around 1820-26. Diane