We knocked the wall through in our 1930s semi, and we love it.
It is THE family room in our house, where everyone meets, where dh and I chat in the mornings when everyone else is still asleep, where homework is done, etc.
If I had an endless pot of money I'd extend the whole room out into the garden, to have an even bigger kitchen/diner.
Do you have an utility room? Somewhere the cat/dog can come in where you can put a sink and their towels?
Yes, most likely this wall is loadbearing and needs a steel. Then you'd need a plasterer. Probably also a plumber if there are radiators on the wall. I have no idea how much ours was, as it was just one part of a major gutting process, rewiring, replumbing, etc.
Our living room doesn't feel small in comparison, as it's almost clutter free. It's just for watching TV, and playing games.
In short, I'd do it again.