Hopefully we can answer some of your questions.
To know whether you are OK to drive a motorhome you will have to try it.
The easiest and quickest way is to go to a motorhome dealer, and suggest you are interested in buying one, and test driving it.
If this isn’t enough time for you to make a decision, then perhaps rent one for a day or weekend, and then you’ll have a better idea of how it drives for you.
Motorhomes are wider than campervans, and so require more care in tight lanes. However, the extra space of a motorhome is worth it.
There is no reason not to holiday is a campervan if you your wife has leg pains. It’s a great way of getting around at your own pace and convenience.
Many campsites are dog friendly, so just choose the ones that are.
There are loads of great motorhomes and campervans. I would recommend renting one, finding out what works best for you, and then finding one that suites you. Don’t worry about the brand or chassis.
In the UK you can easily use a 3G dongle, which allows laptops to connect to the internet. Three are probably the best.
Some campsites have WiFi, but it’s often only at the reception, and can be patchy.
I think post Brexit we will be able to travel in all European countries just like we do now.
Try a motorhome. The dealers do finance plans, so hopefully that will work for you.