I live in Dover part of the time, did the Calais run at least five times every year for many years.
From Ramsgate, first you have to get round the Goodwin sands, then across the Dover Straight TSS. The two keys are these. First, by law you have to cross the TSS on a heading that is at right-angles to it. You'll see on the chart this means departing from somewhere near South Goodwin lightship (though the lightship has now been replaced by a buoy). So first you have to get there. Second, if you want to enter the marina at Calais, the lock opens about 1˝ hours either side of HW, so you aim to arrive near high water. And it will take about 5 hours to get there from Ramsgate.
Leave on a rising tide shortly after low water, go east then around the outside of the Goodwin sands, coming down south with the help of the tide to somewhere a little to the east of S. Goodwin. Then aim straight across, letting the tide carry you the rest of the way westwards.
The Dover Straight TSS is the busiest in the world and is a daunting prospect first time given the number of ships. Don't try it in poor visibility or at night (first time). You must have an engine capable of giving 5 kts even if you actually sail. If you try to wait until its all clear, you will wait forever, so you must head out and expect to take avoidance action en route.
Ships in the TSS WILL ASSUME YOU ARE MOTORING whether or not you actually are, and interpret the Collision Regs accordingly. This means in the first, west-going lane they will give way to you. But beware some to do not, and some can't because of the number of ships around them - so never forget ColRegs Rule 10j: "A vessel of less than 20 metres in length or a sailing vessel shall not impede the safe passage of a power-driven vessel following a traffic lane." So watch like a hawk, if you're within a mile of a ship and still seem to be on a collision course, make a major change of course (I turn right round) and wait for them to go by. In the second, east-bound lane it is easier because you are the give-way vessel, so you just keep clear of everything by at least half a mile.
You'll be reaching Calais near high water so the shallow bank (The Ridens) outside is not normally an issue. Go up to the harbor wall but as Calais is a very busy port DO NOT ATTEMPT TO APPROACH THE ENTRANCE until you have received permission from port control on VHF
ch17 before entering. They speak good English if your French is limited, but may keep you waiting awhile.
Once inside, you stick to the right-hand side which leads to the marina. At present the lock gate to the marina is broken so the marina is out of action. However there are mooring buoys just outside you can pick up. Its a bit smelly there at low tide from the fish dock and you'll need a dinghy
to get ashore, but otherwise OK.
As I said, The Dover TSS can seem daunting, but I can never remember a case of a yacht getting into serious trouble out there. Everyone, ships, ferries, fishing boats and yachts, is very much on the watch. But if you do have doubts for your first crossing, you'll almost certainly find a local yacht willing to buddy-up to help you. Ask in the Royal Temple YC.
If you blow it on the tide, then it may be better to take the inside passage (via buoy B1) down to South Goodwin at first. This is OK, but remember there is now an 'advisory' route for the cross-channel ferries out of Dover that you should avoid straying into as you go across the TSS. There should be a chart showing the position of this route pinned up in Ramsgate Marina and RTYC - it isn't yet marked on regular charts