Can't answer about Bombarral - never been there, and as the question has gone unanswered for a couple weeks it seems safe to say not many of us have. I'm in a slightly larger city on the other end of the Leiria district, hence much farther from Lisbon (but better connected by train.)
There are a few other residents where who are native speakers of English. We know of a couple right here in town. When they got here, someone told them they were the only Americans in the city ... this was after we moved in, so it was an erroneous statement, but we don't know for sure how many there are either. For practical purposes, there's no noticeable English-speaking expat community.
Some of the Portuguese nationals here are able to speak English reasonably well, and may be happy to get a chance to exercise this skill. Many simply do not speak English, or not enough to be comfortable trying. I'm fortunate to have spent a long time working up Portuguese language skills; to me it seems like it would be incredibly frustrating to live here otherwise. If people come to work on your house ... sign language? The police don't speak English, hopefully this will not be a big problem as they're mostly a lost-and-found department in this quiet city, but - imagine. And if anyone can pick it up to a useful fluency in like six months or something, it isn't anyone I've met. We know a few who have basically given up - it's hard.
We know a couple in Caldas da Rainha, not very far from Bombarral, and I sort of envy their much better social integration if that's the right term. They're learning the language as well as anyone we know, probably better, but the barrier isn't as bad. They're right in the city. It's more cosmopolitan, more people speak English, more people have other things going on besides 8 hour jobs and raising children. The competition for good places to live is much more intense, because everyone wants to live there.
This is not to say Bombarral is a loser. I had to look at this, because I had really skipped over it when I was looking for options, and it looks like a nice town. If there's a lot about the situation you were looking at that really has you hooked ... maybe you'll be fine there. The Portuguese are no different there than anywhere else, the nicest people in the world, and they certainly haven't been burned out on expats in the way that could happen in e.g. the Algarve. A lot depends on what you're like, really.