Yes the UKV is factoring a few homegrowns in the heat and the elevated. First few storms maybe 7pm south east with more elevated overnight.
Something takes a huge chunk out the temps around 7pm in SE hmmm wonder if that's an expected early import or homegrown rain shower dropping temps
I have seen situations like this over the last 20 years and they never plan out to how models predict. (like asking which corn in the pan will popcorn and exactly when) It could form over Bristol and hit Midlands missing SE, it could form over Belgium and miss UK completely. no one knows.
Good point MCS can sometimes form/get caught up in the frontal system. (don't think that will happen today though) depends how much heat is drawn up in front of it.
Yes the West get homegrown decent storms, the SE usually get the imports. (Elevated)
Although sometimes the SW, Bath, Bristol, East Wales has a good knack of developing Elevated lightning shows.
Models struggling with the plume I think, temps of 6C in Wales but 30C just over channel in France are unlikely
If I was a betting man I would say plume of hot air wednesday/thursday with quite severe thunderstorms in places giving a cool down to 15, 17C