Hi Nicky. Welcome back.
Have you firstly contacted the RE Museum? There will also be an association as well, all easily found thrugh a google search. Other than that there is the forces section of friends reunited (Forces Reunited) on which it may be possible to find ex members of the same group.
In order to find out what where the 101 RE were based throughout the war you first need to access the company Operational Record Book (ORB) or somesuch similar item, which is most likely now to be held at the National Records office in Kew. Drop them an email and ask. If they don't have it they may be able to tell you if it is still in existence and where it is. Next contact the museum, there is always an expert there who can tell you who was doing what, where and for whom at any point. As the person you are researching fell during th Caen offencsive then there is an excellent chance there are some very good records of what was happening to the 101 RE at the time.
I hope this is of help, and I would normally have done the links for you but am at Uni and the system is sniffy as it is.
But just a basic google search for Royal Engineers, RE Association and National Records Office will get you the links.
