Hey,

Tues-Thurs is fine. I actually quite enjoy mixing countries up a bit. Do much more than that with a family and you'll soon become a stranger though.

I tend to prefer leaving the night before as I don't like early mornings, but as you have family you will almost certainly rather go for the early flights. Remember you lose an hour going to France, so you will want to take the earliest flight and hope you're going somewhere near to the airport!

I don't know how it works at Birmingham, but in Heathrow (with fast-track security access) I would tend to arrive about 45-50min before departure. Every now and then I'll miss a flight if something gets in the way of my journey, but relatively rarely.

In terms of booking flights, I would tend to do 2-3 at a time to save on admin - I'd also do expenses at the same time as otherwise I found myself doing 15min several times a week just on logistics which drove me mad. If you are senior enough to have a secretary of course I'd just leave it to her to figure out.