The thing that catches people out usually isn't the provider, it's a couple of clauses that are easy to skim past when you're comparing prices.
Check whether the policy requires the trip to start and end in the UK. Most standard UK annual policies do, which means a trip your DC takes from their host city to somewhere else isn't covered at all, because it isn't a journey that began here. That one clause rules out a lot of otherwise sensible policies, and it's why Big Cat keeps coming up on threads like this one.
Check the maximum trip length too. "Annual multi-trip" sounds like it covers the year, but they nearly all cap any single trip at around 30 to 45 days, and an academic year abroad reads to an insurer as one long trip rather than a series of short ones.
It's also worth knowing you may be comparing two different products. A travel policy is for emergencies and getting someone home. What ealingwestmum was quoted is international private medical insurance, which is closer to ongoing healthcare cover while living somewhere. For a full academic year the medical plan often works better as the base layer, with something separate for the trips away.
On the sport, don't just check that it's listed. Check the level. Plenty of policies cover a sport recreationally but exclude it played competitively or for a club or university team, which is exactly what your DC is likely to end up doing if they join anything out there. Anything on snow is nearly always a paid add-on.
Two smaller things. Most UK policies require the insured person to be UK resident and often registered with a UK GP, so read that wording carefully if they're away for nine months or more. And if it's an EU country, a GHIC is worth having alongside, since it gets state treatment on the same basis as a local, but it isn't insurance and won't repatriate anyone or pay for a missed flight.
Last thing: don't cancel the university policy and replace it. It's often the thing that satisfies the host institution's mandatory insurance requirement, so treat whatever you buy as a layer on top of it rather than a swap.