No disrespect, but can you be a bit more specific in what you mean by a euro adapter. Euro is the currency of the EU so unsure how that is connected. Ok, only kidding.
Most of Europe use the Schoko 2 pin plug and socket and you can get adapters anywhere in the Uk to allow you to use your 3 pin equipment in them. As for a mains cable then any accesory shop will sell you an adaptor extension to allow you to connect your blue plug to a mains point. However, in France they still have on many sites their own 2 pin and earth plug and socket and it would be a good idea to get an adapter extension purely for France. You can either buy one, or if you have a rough knowledge of electrics, buy the plug from a supermarket and make your own. Many of us make up 2 extensions, one with reverse polarity as this will often occur on French sites, or make a crossover. It is more complicated to describe than actually do.
However, do get a polarity checker plug from any accesory shop and use it to check what you actually have on a given site. It will not stop anything actuilly working, it just means that the fuse breaker could be on the outlet side instead of the inlet and therefore in the event of a fault, you could get an electric shock. In Europe they have double pole breakers so it does not matter. It is also useful to tell you everything in your van is fine, you would be surprised as to what you may inherit. DIY is not always a good thing.
If you ahve a friend who has been to Europe with the van then ask for advice as to what they did.It will be a start. The CC or the C&CC are also good points of advice.
Go to a major caravan accesory shop and tell them what you need. They will be happy to assist you.