Frankly, it will be a lot easier for her to meet Polish couples who can speak English than British and mixed couples with children living in Wrocław. While I'm sure the latter do exist, I never met any. The only English speaking foreigner I met with family was an American who came years ago and married a Pole.
There is a facebook group called Expats in Wrocław, but it doesn't want to load for me at the moment. There is, or was, also a group called International Friends of Wrocław. I'm sure that if you get out there and look for them, you might find a couple of British or mixed couples with kids. Check with the international schools. You might want to ask around at the British and Irish Pubs on Plac Solny. There is also a Scottish pub across from Renoma. Never been to any of them, so I can't vouch for their authenticity, but they might be able to put you in touch with some. There might be a couple of academics at the universities, too, though I never met or heard about any.
There is no British "community" in Wrocław. There are scattered Brits of various sorts, but nothing that resembles a community. If she thinks she is going to be able to operate in an English speaking bubble long term in Wrocław, and isn't gung-ho about learning Polish, then she has another think coming. You might want to reconsider moving to Poland if that's what she expects.
Most of the Brits in Wrocław fall into two broad classes: 1) Employees of British companies that are deployed short-term as consultants and technical specialists. If they have families, they practically always leave them at home. They're there to get a job done and aren't interested in socializing. And 2) assorted flotsam and jetsam, young backpackers, slackers, horny boys hoping to score, idiots who came to Poland with their Polish "girlfriends" who told them they could strike it rich there. Predominantly single males, often with alcohol problems. Not the type of people you're looking for.
Actual British and mixed couples are a distinct minority, and those with children even fewer. If you're planning on staying in Poland for long, then your wife should intensively study Polish, morning, noon and night. Even if she works her a$$ off, it will take her a few years to become conversant. Be super-ultra-supportive and helpful, and make sure you never, ever do or say anything that will turn her off, or else she will slam that book shut and never open it again, and will be on the next plane back to Scotland. Be patient, but constantly motivate her to keep working hard at it.