I now have one ready for when I go in a few weeks! Looking at where to place it as I have rain sensors I have to place it on the big plastic section of the wing mirror but at least its all done!
Let me know how you get on Kev. I'm unlikely to have a 'Pete' for Le Mans, so a Peage tag will be the easiest way for me to go (did it take long to arrange/get delivered?). Plus I'm heading back to France for the family summer holiday as well as a planned trip to Somme area later in the year too. For the last two I'll have a 'Lisa' model of the 'Pete', but if I have a tag it'll mean the 'Lisa' will be able to concentrate on keeping an eye on the 'Kids'. 
I literally rang these -
https://www.saneftolling.co.uk/Based in England in Harrogate!
Rang them, explained it idiot proof I then went back to the website and created a account it arrived in a day or 2. Expensive to start with IMO as first 2 trips cost 5euro per trip for the tag then your tolls on top.
from memory it was 11 Euro to create a account / set it up and 20 Euro deposit for the tag. Once you return the tag you get that back. The first payment went out of my account on DD today for £31.63 (it converts the euros to ££ by the way)
I used my friends in September when my dad passed away as he had it still and I was in a rush, So So So easy, roll up to the barrier you get a beep, it opens and carry on. Once home end of the month you get a statement and the funds are taken. If I was doing 1 trip i wouldnt of bothered due to the cost but as I am off in April, June & maybe July and September its worth it