I have just been talking to my son who's a civil engineer working on the M1 widening project J10 to J8 and he says there are to be lots of overnight (21:00-09:00) closures on Saturday nights over the next 8 weeks so if travelling down to catch flights be warned and check ahead as its not every Saturday but most of them. The closures are from J9 to J8. So you should be OK coming south to Luton as its J10 exit but it may back up so be careful.