House-calling etiquette

I am to visit a Japanese family by invitaition, and I am aware of a phrase used when entering their house, but do not know what it is in Japanese. Its' literal translation is 'Sorry for the interruption', But I cannot find the correct Japanese phrase.
HELP!!!

England Al,

"Ojama shimasu!" is probably what you are after. It is often uttered when entering someone's house/room/office.

It is "Ojamashimasu." Don't forget to take a small gift, usually something to eat--a box of Japanese sweets, rice crackers, chocolate or even cakes.

i would prefer bringing some specialities from your homecountry with you. for women chocolate is a good choice. but men prefer (usually, i know that there are a lot exeptions) foreign beer....
looking at your name, i would say, that you are from england. so, strongbow cider would be great!
sorry for this advertise.