I do it several days a week as I live just south of Luton zone, rotary and work up north.
You can route via Panshanger overhead (bit tricky to see until you're right on top of it!) to hit the south east corner of the Luton zone, then Walkern village, Biggleswade then hangar left and on you go. 2,000 ft.
Contact Panshanger first to let them know you are coming over, then get on to Luton. I contact Luton 50% of the time for flight information svc, tell them I'm routing east of Stevenage and remaining clear of controlled airspace. You can happily fly past with just a listening brief on Luton 129.55 (I may regret saying that...
), although you may then hear a call letting someone else know you are there (unidentified traffic). If you hear that, it's polite to call in and let them know, to make sure they know who you are and your intentions as you are clearly in someone's way.
There's not a lot of time to be saved going through the zone and it's a lot less stressful.
The corridor is pretty wide, don't exceed 2,500 or go too close to Stanstead side (1500ft there). It's not that busy, but worth keeping a lookout more to the north/south, because stuff generally goes that way.
GPS helps...
BW