Comedy genre certification

As a group we have decided our film that we are going to make an opening for, will be a rural comedy. To aid our research into the genre, we have decided to look into certifications of comedy films, to see if there is a generally given certification for comedy films. This will help us decide the classification for our film opening.
These are some recent popular comedy films:
Stupid Crazy Love - 12
Bridesmaids - 15
Johnny English Reborn - PG

The Hangover - 15
UP - U

Grown Ups - 12
Some other popular comedy films:
Forrest Gump - 12
Mean Girls - 12

Home Alone - PG
Meet the Fockers - 12
Shrek - U
Bruce Almighty - 12
Mrs. Doubtfire - PG

As you can see there is a huge mixture of different certifications for these comedy films. This is because comedy appeals to most people, meaning institutions need to make comedy films for all ages and types of audiences, unlike a theme such as horror, which is restricted by certification due to the fact, the more of their genre is put in, the more restricted it is for audiences. I think the most common certification for a comedy film is a 12, i think this is because some a lot comedy can tend to revolve around stupid behaviour and bad language. I have discovered that comedy is a genre that is open to all, but you can restrict you audience with the type of comedy used, i have learnt that we now need to decide as a group where we are going in regards to our film and the comedy genre.