With Motorhoming - as with everything in life - we were all newbies once
And it is great fun learning the ropes and discovering how the whole thing works
My general advice is something like this
Learn about how all the habitation area of the motorhome works - water supply, gas supply, where the habitation battery is, how the heater works, how the water heater works, how the toilet system works - all that kind of stuff. If you do not have the manuals that came with it when new ask someone to go over it with you. There is lots of info on the internet
Make sure your vehicle is mechanically sound and safe and make sure all the habitation bits are serviceable too.
For camping it is best to start with local and short trips. So just go off for a weekend every opportunity you get. These trips get you out using and testing all the functions of the motorhome. If something is not working right well at least you are only 50 miles from home. There is nothing like using a motorhome out camping to check that everything works.
You could then try a week long trip here in Ireland before venturing abroad if you have time. This will give you and your motorhome a good test on how everything is working. Making sure you can fit in the equipment you need and leaving out all the equipment that you do not need. It might be a good idea to weigh your motorhome - front axel only, both axels and rear axel only, to make sure you are not over the weight limits for your motorhome.
Before you go abroad - a service and general checkup would be good unless you have done one recently
For a first trip abroad a trip down the western side of France to the Loire would be a great start. (The Loire is about 300 miles from Cherbourg) From there you could go inward and explore some of the Loire Valley or if you prefer the beach you could go down as far as La Tranch sur mer and that coastline. On the way down or back up you could visit the Military Cemeteries in Normandy
A trip like that would get you used to driving on French roads and gain a knowledge of French way of life. And it will whet your appetite for more longer and more adventurous trips in the future
Happy Camping