Most of us in Britain had never heard the term hockey mom before last weekend. And many probably still don't realise that hockey refers to ice hockey not the sport traditionally played on a field at posh girls' schools. In Britain, you would say ice hockey if you meant the rink sport. And there's no need to say field hockey or hockey with a ball (as Russians say), as that's the default meaning if you just say hockey.
I've just googled hockey mom, and am still not entirely sure I've grasped all the nuances, but I can't think of the equivalent in British English. We'd probably say 'pushy parents', but that's a negative term. Hockey moms, I presume, are prepared to drive their children to games, bake cakes for visiting teams and support or console their kids through the highs and lows of winning and losing. I imagine they are proud, fiercely protective and assertive. And competitive too! I got a taste for the rivalry between soccer moms and hockey moms just by a simple internet search.
Of course, I watched my children play sport too when they were in school (netball, hockey, football, rugby, cricket and tennis, depending on season) and baked cakes. But I don't recall ever defining myself or the other mums by those activities. Certainly there is a minority of parents who take the whole thing far too seriously, challenging the ref's decisions and scheming and wangling to get their child in the team, but it's not just mums. A new sitcom has just started on BBC2 called The Cup, and it is about the pushy parents (dads mainly, I think) of an under-11 football team. Note that in Britain we regard the subject as comedy material!
There's a phrase in British English, jolly hockey sticks - used mostly as an adjective (as in 'she's a jolly-hockey-sticks type') and a not very complimentary one at that! It harks back to the days when hockey was associated with girls' grammar or fee-paying schools and evokes the qualities of tenacity, fortitude, grit, grinning and bearing it, making the best of things, putting on a brave face (everything must always be jolly!). The schoolgirls in Enid Blyton's stories typify the attitude. Joyce Grenfell, a popular comic actress of the 1960s, famous for her comic monologues, had a jolly-hockey-sticks image.
It's a shame that it's a derogatory term nowadays. It is rather dated, but it symbolises strong, independent and self-assured women - just like America's hockey moms, in fact.