A suitable injury

Gunshot wound is the first thing that comes to mind, followed closely by an abdominal stabbing. Lots of bacteria in the belly, so lots of opportunity for infection. Peritonitis can be very bad.

Can't speak to UK hospitals. In the US, he'd be in an ICU, and while the official rules typically involve visits of 10-15 minutes limited to 2 people at a time, the length of the visit usually has some flexibility.

Any kind of head injury where he lost consciouness could result in a stroke a few days later.

I agree on the head wound. Just getting knocked down could cause it, and it could lead to a huge amount of trouble. Even without a stroke, it could require weeks in a hospital and more time in rehab.

What ward they are in depends on the severity of the injury

ICU is for critically ill or unstable patients. It would need to be an injury that is immediately threatening to his life. However if he's there, visiting times are flexible (and if he's undergoing treatment etc, there are usually waiting rooms/places to be nearby) Here's the NHS page re ICUs, what to expect, visiting times

If his condition is serious but not immediately life threatening or he's stable, with a severe injury he might be on a high dependency ward. Visiting times are usually limited (Here's an example) which allows doctors and nurses to go through their routines with no visitors about. General wards would be much the same re visiting hours. So the wife would still be able to be at home some/quite a lot of the time, depending on how far away the hospital is.

I agree a head injury is a good way to go. Make the burglar gave him a whack with the candelabra? The NHS page about head injuries should give you a place to start.

Blow to the head, hospitalized for observation; subdural bleedings can take a while to manifest/cause trouble.

Half jokingly, half seriously... A serious kick to the boys.

A really good hit can rupture the urethra and crack the pelvis. If both of those happen he'd be hospitalized for the surgery to fix the piping and observation after. He could also develop blood clots that could cause a stroke or all kinds of problems in the lungs. But ultimately, that'd be something he'd recover from, though he'd be walking kinda gingerly for a few days.

A poker? TBH, if I read that he'd been hit with a poker it would pull me out of the story cos I would be wondering about what kind of house they live in. And would a lot of kids these days know what a poker is?

If you want something to hit him with that you would find in your average house, you'd be better off with an ornament. I have a figurine of Miranda that would kill someone if I hit them with it.

In the UK, I'd go with a cricket bat before I thought about a poker.

A cricket bat signed by the team that won the county championship in.....

A cricket bat is usually swung two-handed. Could easily break an arm if the victim raised an arm to protect themselves from the blow, or a skull fracture if they hit the head.

Only with a punctured lung. Cracked ribs are not usually serious enough. Although an embolism (sp?) might contribute to a longer stay.

I've got my schooldays hockey stick next to my bed (tucked in a corner) - you never know when you might need to to giveone a good whack round the chops! There's also a hammer underneath the bed as a back-up.

My neighbour keeps a proper American wooden baseball bat next to her bed when her husband goes away on business - he got it for her on a trip to the US as he knows she gets edgy.

I'd like to point out that we live in a decent low-crime area -- honest!