You are too cautious.
It depends entirely on what other IMC there is about.
If there isn't any i.e. it is just CBs here and there, what you will have (UK/N European context, not Florida or Africa!) is some huge clouds, well scattered, with bases around 2000ft, very rarely lower than 1500ft (and rarely higher than 4000ft) and you can fly around them easily, or even under them if you want a 100-150kt car wash and get chucked around a fair bit. And the one you don't want to go under are obvious; the gap between the bottom of it and the ground is one solid column of water
So, VFR, not a problem, unless you get one close to departure or destination in which case you need to wait a bit. You don't want to be doing a landing anywhere near a CB (wind shear).
IFR is much worse, because you could be in IMC, and in any case under ATC control, and fly into an embedded one. I scrap any IFR flight where CBs are likely or forecast, unless the conditions as as in my VFR scenario above in which case visual avoidance is an option. There are problems with that though because of lack of online data on cloud tops especially with this kind of weather around.
In short, CBs are a non issue if you have lots of empty space to go to instead.