The school have a trip every year which the year 2's walk down to our local church - its not for a service but they have a look around, see whats in a church etc. It toes in with the R.E topic that year.
Some of the parents of this years year 2 are complaining and have started a petition they asked people to sign against the trip - there are three Mums who have organised it and they are all atheists.
Now I could understand if they were going for a service, to pray etc - but its just a look round type of visit (I know because I volunteer at the school and have been on a few of the previous trips. Also, The years 3's attend a synagogue and year 5 pupils attend a mosque. Its more of a learning experience because it ties in with what they are doing in school.
At the very least, if you dont like it, dont go - but a petition seems a step too far to me.