I have lost the keys to my R6 whilst touring in Spain. How easy is it to get a spare set. Would a locksmith be able to cut a blank for steering lock and petrol tank. or would I need a main dealer. Please help

That Sucks!!!
You're going to need the key code blanks from when you originally bought the bike inorder for a dealer to make spares without a match. If you don't have those, you could try contacting the dealer who sold the bike originally, they may have the codes on file.

Disaster. It is an bike originally bourght in Switzerladn, imported to Scotland that I am touring with in Spain.

Is it possible to get full new locks and barrels from a main dealer?

You can. But it's a huge pain in the ass. You have to drill or hammer out the rivets that hold the ignition in. And pick the lock on the tank. Then replace the tank cap, and the ignition.
You could try to get the tank picked and replace that with a vortex race cap... no keys needed. Then unplug the ignition and run a jumper wire. You won't be able to lock the bike and you'd have to hotwire it every morning but it would be a cheaper alternative.

When I downed my bike I needed a new trunk lock, I ordered one from a dealer and ironically the new trunk key will open the tank and also start the bike. I would try and take your tank lock to a dealer and see if they can send it to yamaha and have a duplicate key made. Or you could just buy a ignition, tank lock and trunk latch over ebay. I've seen people selling complete key sets from totaled bikes for under 100 bucks.