He does not want to work

Of course you're not unreasonable. I have a severe knee issue and have had several surgeries, walk with sticks or crutches as assistance a lot of the time if I'm out the house, painkillers most days. I work full time I just work in a different job than I did before I had my issues as I can't guarantee mobility/ability to drive every day, but I can absolutely sit at a computer and it's a better time than ever before if you have a physical restriction to work flexibly and/or from home. He doesn't want to work and he can leech off you so he doesn't. He's made it clear he's not going to change so it's your choice now if you live with this situation or you leave, but you can't make someone else change. Good news is you're not married so it's a lot easier for you to leave if you choose.

Not sure why OP but your use of he, he, he , he throughout instead of partner etc has given me the ick 🤣 never seen anyone post and use he throughout without referring to who he is 🤣

He is a lazy bastard cocklodger. You would be better without the deadweight. LTB. I'm sorry you are left with someone who clearly doesn't give a shit about his family. Good luck OP x

@what2do2donow what is your housing situation? If you own the property, he needs to leave, or contribute. Rented, what is the tenancy situation, can you move and rent alone?

Lazy f*cker.

Are you married OP?

To answer the job question, he can do ANY office job/wfh job. Literally thousands he could do.

So you can work from home, but him working from home (ideal for his knee!) is a non starter? He's not cooking / cleaning either?
What a poor example he's setting his kids.
You've got to make it non negotiable that he looks for work. Get him up early every day to help with cooking and cleaning until he does. It's laughable that he can't miss a football match but he can't find a job?

Because he's happily leeching off his girlfriend, who's allowing it. Hopefully OP will see sense, raise her standards and dump the pointless slob.

Of course you're not BU. Has he not noticed that there are wheelchair users who work full-time? And blind people, and deaf people?

To your last point, my partner is in his mid 40s and has just been approved for a hip replacement. I think it is worth having a consultation because whether they agree to do it or not will depend on the severity of the problem and impact on quality of life, not just age.
But it seem there is a bigger issue than just pain.

Why can't he do a desk job?

YANBU for expecting a 40-something year old to financially support himself and his children.
What's his plan for his future? Pension? Is he just going to watch football from now until the day he dies? What a life.
Leave, don't look back. You deserve more than that

It's not actually your job to offer him "a work idea suitable for his condition". He is an adult, he does not need a nanny. It sounds as though his arthritis is pretty bad but if he can sit at home and watch TV, then he can sit at home and do any WFH job. He can as the GP to refer to pain management service. He can access national careers service, vocational rehabilitation, FE course... There are hundreds of things he, as an adult, can and should do. It is not your responsibility.
So yes, unless there is a significant issue you are not telling us about (like, depression for which he is getting support) then I would move out. Or kick him out. Depending on who owns the house.

emsantana99 , it's HIS responsibility to keep himself alive. Get rid. x

Ok, so a number of things,

Firstly in the U.K. there is no such thing as common law husband. What you have there legally is a boyfriend. Unless you own the house together then you can just kick him out.

Secondly, if he is in serious pain and it's impacting him badly, such that he cannot work (and I don't know if this is the case) he can claim contributions based Employment and support allowance which is for situations when someone is too ill (either temporarily or permanently) to work. If he has the right level of contributions then a year is automatic and he may get more time/more money if he has other issues (which he clearly does)

Thirdly, there are plenty of jobs you can do without walking but he'd need to have the skills for them and a lot of jobs do just reject anyone disabled as too much hassle. Again, if he contacts the job centre because he has a physical disability they may be able to offer a specialist disability coach who can help.

Fourthly, the nhs rations knew replacements quite hard. I know someone who can't work in his normal job (gardener) as he is waiting for a knee replacement but the nhs won't do it until he's older because otherwise it might wear out before he dies. So he's on benefits and in pain while he waits.

Taxi driving could be the way to go. My DP has severe mobility issues, previous stroke and it was about the only job he could do. He occasionally did mini bus driving for disabled clients for the LA. He should be running the house.

Is he claiming PiP/Low capacity to work? Is he actually signed off work officially? Because if he is you’re being unreasonable. If you feel he’s actually mooching that’s a different matter, you may as well separate because he doesn’t sound like he’s bringing much to the relationship.

There's no such thing as a common law husband. He's your boyfriend or fiancé if engaged.

Ask yourself - what positive impact is he having in your life? If he's at home is he doing all the housework, cooking all the meals? Doing all the childcare?

If he's not working why are you doing the cooking? He's a lazy, selfish arse. Kick him out OP.

Mid forties ? Lazy b***d.

He sounds lazy. I can’t work due to autism but I make sure I do everything in the house and to do with the dc and all admin etc . He sounds like he’s just watching football? Maybe have a stronger worded conversation and give him an ultimatum?

So you are surviving on your wage only?

Are you working?