GETTING THERE

CHARTER FLIGHTS

Normally the cheapest and easiest option for getting to Crete, and indeed back home again. Direct flights are only available during the tourist season, currently late April to the end of October. There is certainly no shortage of these. A web search is probably the best way of finding a good deal. Don't discount package holidays, especially if that's what you want of course. But sometimes a package tour can be cheaper than a flight alone, and there's no compulsion to stay in your allocated accommodation. It may be advisable to inform a travel rep. of your intentions, just in case they are having a slow day selling excursions and decide to organize a search party

SCHEDULED FLIGHTS

Invariably scheduled flights transit through Athens, with a few exceptions flying directly to Iraklion. Unless you want to stop off in Athens, there is little point in taking a scheduled flight, as they will probably be more expensive and will definitely take longer. Outside of the tourist season of course you won't have any choice, but the island is very well served with flights from Athens with six flights a day to Chania airport and more to Iraklion.

FERRIES

The northern coast has a fairly comprehensive ferry service to the mainland. There is a daily ferry from Piraeus ( the port of Athens ) to Chania, Rethymnon, and Iraklion. The journey takes around nine hours. There is a service, albeit somewhat erratic from Kastelli to the South Peloponnese islands, and between April and October ferries run to Santorini and the other Cycladic islands, from Iraklion and Agios Nikolaos.
In winter ferries can be delayed by bad weather.

OVERLAND

Not an option for the faint hearted, but if you're interested in seeing the places along the way, or have bought a house in Crete and want to get your belongings out there, this may be for you. The quickest and most practical route is from Calais to Venice, then from Venice take the ferry to Patra in Greece. Drive across to Piraeus, and take the ferry to Crete.
You can of course drive directly to Greece through the former Yugoslavia, or through Hungary, Bulgaria, and Romania. This is obviously a much longer and therefore expensive drive, with nothing to commend it unless you particularly want to visit these countries on route. I would do extensive research on political stability and customs requirements however if you plan to take this route.
Below is a suggested route through Venice.

From Calais taken the A16 towards Dunkirk. Then turn right on the E42 towards Lille.
Stay on the E42 passing Mons and Charleroi. Close to Namur is a junction with the A4.
Turn right onto the A4 and follow it to Luxembourg. From Luxembourg take the A8 towards Saarbrucken. Stay on the A8 through Karlsruhe and Stuttgart until you get to Ulm. At Ulm take the A7, then the E60 to Innsbruck. From Innsbruck take the A22 towards Bolzano. Follow this to Verona, then take the A4 to Venice.
Take the ferry from Venice to Patra on the Greek mainland, then follow the 8A all the way through to Athens and Piraeus, passing through Korinth, with it's famous canal. Then from Piraeus take the ferry to whichever port of Crete takes your fancy.
The distance from Calais to Venice is approximately 950 miles, and the distance from Patra to Piraeus is approximately 130 miles. Giving a total mileage from Calais to Crete of 1080 miles. The ferry from Venice to Patra takes around 20 hours, and the ferry from Piraeus to Crete takes around 9 hours. If you are intending making this trip it will be well worth researching current driving regulations, and gas and accommodation prices in the countries you will be passing through.