LARS is a fantastic service that I use where ever possible to get a RIS or FIS.
You can get handed from unit to unit, if they have you identified, but you have to ask and often you'll just be told to freecall, which isn't much of a problem, though it is nice to handed over.
Unfortunately the LARS coverage in some areas is very poor and is much reduced with the loss of so many RAF stations.
I recommend that everybody uses it, especially if in IMC OCA as it can be a life saver. In fact I wouldn't go into IMC without it.
I'm very concerned that you did an IMC course and have not used the service. Don't worry about using it, they are there to help and very rarely bite!