I had been flying eight years before I did my first crops-channel flight in 2016. It waited until I was in a share because I was blowed if was paying to go to Le Touquet with an instructor when I was in a club. That aside, when I did it, it was no different from any other flight. Follow the legal requirements for stuff you must carry and what you must tell the authorities and you'll be fine. I would support anchohold in suggesting Belgium. My first foreign stop (well not counting going to Donegal from Derry which is officially international) was the marvellous Kortrijk. After reading so much about prior-notice and such like with France, it was no effort at all to continue the extra (small) distance to Belgium. My post-flight report at the time said:
"Stopped here twice on a continental trip recently. A near perfect small airfield. Self-service fuel pumps next to the terminal. A quick passport check to enter Schengen then up to the tower to sign-in. The airfield takes no money on the day, you sign in, log the amount of fuel taken and wait for an invoice in the post. EBKT proved to be an excellent destination. It has border control facilities, a good size hard runway, instrument approaches for those with full IR plus both a flying club bar and an excellent high quality restaurant called Biggles. In addition to plenty of light GA, there are based business jets and I think over in one corner a small military facility (we could see a Skyvan / SD3-30 and a Gazelle). We twice ate well at the Biggles sitting in the sun on the first-floor balcony . The flying club bar and the control tower are built onto what I take to be a German wartime concrete bunker. The Bell X1 hotel is 100m from the airport buildings. It proved to be as good as it looked on its web site and had the added interest of rooms named for pilots (and in one case a RAF aircraft repair unit which was based there in 1944 / 5). The building itself is a rather interesting between the wars design. The only slight disappointment was a rather thin breakfast."
I have a vague memory that the instrument approaches have since been withdrawn.