God this thread 
I am definitely a prepper (I remember lobbying for the Prepping board!) and like to prepare for every scenario but a stretcher at home seems ridiculous. There is much more useful action you can take if you want to prepare (the first one is to contact your MP about the NHS crisis but that's a whole other thread. My MP hasn't even responded even with a holding reply, to an email I sent beginning of October following a hospital visit 
)
I would love first aid to be taught in schools and it's worth lobbying for that too! If anyone has specific concerns about a loved ones health condition and A and E trips, their consultant/GP should be able to signpost/help with a Care Plan. It makes 999 calls much quicker as you can read out info which has already been summarised (especially in a stressful situation). IME 999 call handlers (appreciate it may be different atm) are good at advising any first aid and talking through steps if you're inexperienced. It also makes admission a lot easier as regular medication/treatment and HCPs details are on there. It's worth always having a ready Hospital Grab Bag with hard copy of Care Plan, essentials like underwear and toiletries, bottle of water with a sports cap, power bank etc and xx days of medication. For people with regular meds, a dosset box is good for seeing when they last took their meds (especially if they're unable to tell you).
PP mentioned adaptations to prevent falls etc in the first place but I don't think it's been mentioned that in most locations Red Cross places can usually provide/lease things like raised toilet seats and grab handles etc.
My GP has said some people who are frequent fliers to A and E, at the current time can have doses of "rescue" medicines and emergency pain relief in the house to factor in delays. I wouldn't go so far as a stretcher for all the obvious reasons listed on the thread, but PP suggestion of crutches (especially for liable to fall people) and maybe a sling etc. Obviously the usual first aid kit in the house anyway. I don't want to be insensitive (I have one myself) but if there is a situation where resuscitation may be involved, esp with very sick or elderly patients, having a clear DNR marked on a Care Plan or just in the house (in writing) as well as NOK being aware, makes things a lot easier for paramedics and loved ones. It would be interesting if any paramedics have any advice for this thread?
I am a frequent flier to A and E but always try and get there without 999/ambulance wherever possible so I have morphine in the house which helps (especially over the 8 million fucking speed bumps on the way to the hospital!) The Care Plan speeds up admission/triage which also helps everyone else in the queue 
It's important to get triage right, I think a lot of (sorry to generalise, I do it myself too) older patients minimise things in a "oh it's OK not too bad, don't worry about me" whilst clutching a limb or about to pass out and it really doesn't help with being triaged correctly.
At the moment I have added a blanket to my Grab Bag so it can be used as a cushion for sitting on the floor in A and E. (I also saw people queuing outside the door in the cold) I'm also tempted to add one of those plastic ponchos for theme park rides after fainting into a pile of sick (not mine) on the A and E floor which had been there for hours.
these tactics are for symptoms (ironic) and not the cause though. The NHS is absolutely fucked sadly and the people that should be held to account are politicians, it really angers me seeing how much abuse hospital staff/paramedics get. I understand how horrifically stressful it is for patients and loved ones at the moment. It's a good time to discuss things like this and DNRs etc as those conversations can be hard but it can slightly reduce the stress knowing you have plans in place.