Andy - I'm taking the Friday and Monday off too, so it's best to use those days. The drive from here to Wales is about 4-5 hours, we will stop for T & P on the way.Tell me your flights when you get them and we can go from there.
Monday afternoon is definately best, and it gives you the morning to sample our delightful London air (or go to Saffron Walden, which is nicer)!!
LTS