Hi Chris,
Your enthusiasm is very clear!
Your cycling on a broken down bike with no brakes and tyres that were shot to pieces displayed that..... as well as a certain recklessness
You start off saying you're looking for touring bikes/routes/bike packing advice. I don't think you're looking for that at all, at the moment.
I think the advice you need is to slow down!
** The OP also has the same thread running on another forum, so my opinions are offered on the basis of his input on both threads**
Right now, you don't need a bike - you already have one!
You're loving cycling the bike...., and that's great.
You have big plans to make touring a part of your life - that's fantastic and I don't think you will be disappointed. Touring is fantastic!
But......
By your own admission, you know very little about bikes and cycling. I'm not trying to imply that its like rocket science, because it's not, but the more you know the better decisions you can make.
You have a limited budget.
You want to camp.... and start practising after Christmas. In January? February? Winter camping is a whole other kettle of fish!
You want to cycle 100 miles per day, loaded for 4 days in a row. That's optimistic!
Your wife, your cycling partner is not "performing" the way you'd like.
Let;s start with the last one first.
Touring with someone else can be a very challenging experience. Different speeds, stamina levels, toilet breaks, hunger tolerance etc mean that 2 people touring together have to have a good touring relationship otherwise problems will arise. It seems that yourself and your wife are diverging already.
Seriously, it's November. I'm with your wife in not being too interested in going out at this time of the year.
(On that point, and this is probably just me, but the idea of "training" for a vacation fills me with horror! "Practising"

is more optimistic).
Bike/cycling knowledge
Since you have only just started out cycling, it's fair to say that you are at the trunk of the cycling tree. There are a lot of branches on that tree, from leisure to commuting to touring, to off-road, to mountainbiking, to tandems, to folding to recumbents....... the list is almost endless. Right now, you're focusing on the touring branch (and looking for a bike to match) without really seeing the other branches, never mind exploring them. It's highly probable that you will also discover other things in cycling that you want to explore and buying a bike so early (when there is no need to do so) may well limit your choices/options in future. Sitting tight on your current bike will give you a chance to explore more options as your experience expands.
Budget
Cycling can be expensive. But it doesn't have to be. For me, the important thing about being on a budget is not to waste money. One of the easiest ways to waste money is to rush in and buy in haste (repenting at leisure). A bike that is cheap and ready out of the box (a quote from you somewhere) are not the best reasons to buy a particular bike.
Bike touring, is ironically, not so much about the bike! You need gear! Tent, sleeping bag, mat, cooking gear? raingear, clothing, maps/gps, lights, as well as the costs - food, drinks, accommodation etc. Planning a good route helps enormously in the enjoyment level. Back-up plans for the inevitable variations reduce stress.
What gear do you have? What do you need to get?
You're reading blogs of world tourers - make a list of the gear they have that you think you need. Cost it. Then look at your budget again.
Camping
Camping is great fun! I love it. I started camping on the bike out of necessity when my trips became longer and I did not have the money for B&Bs or hotels. Now, it's one of my favourite things.
I also do winter camping. It's a very different experience - cold, wet, no chance to get dry. Short days. Less places to stay. If you're planning on practising in January or February I'd reckon there's a strong chance that it will be a disaster! (Of course, maybe you're an experienced camper and this doesn't apply).
100 miles per day.
I can cycle 100 miles on a loaded bike. I choose not to do it, unless absolutely essential. It's just no fun. Rush, rush, rush. No time to stop and smell the roses. And if the weather or terrain is against you, downright horrible.
Think about it. Average 10 mph. that's 10 hours constant cycling. No breaks. Start at 9 am. Cycle until 7 pm. Stop for lunch? Then cycle until 8 pm. Pitch a tent? Cook dinner? And get up and do it again tomorrow?
To conclude, I think the most important thing for you is to slow down and bring your wife along for the ride.
Tell her to wear what she's comfortable in on the bike. You don't need "cycling clothes". I tour in a pair of
Decathlon shorts and a t-shirt. No padded shorts, bibs etc. The only bike clothing I own is a Gore jacket and trousers I use for winter commuting. Everything else is "normal clothing". I tried some lycra... once. I rode very fast because I was sure the fashion police were on my tail for severe crimes against public decency! Plus, I found the padded shorts to be yucky on tour.
Stick to your tour plan, but reassess closer to the time and plan on using a train(s).
There's no reason you can't use your existing bikes for that trip and use it as a learning experience for cycling the whole coastline.
And finally.......(Honestly!

)
Just on the bike choices......have you considered a tandem? Not for everybody - expensive and difficult to store and transport but can be great for couples.
Or folding bikes? Yes, you can tour on them. Easy to bring with you anywhere. The world really does become your oyster with a folding bike!
Best of luck in your adventures! Just remember to breathe!
