For reasons i wont go into just yet, i will be spending a consderable amount of time abroad in the next 2 1/2 years potentially. Apart from the obvious putting the car on blocks, what else should I do? With outboards we put fogging oil in the bores..

I am going to get the car inside a dry barn with good air flow for this hopefully, the other option is sell it, but for me that is not an option..

Ill probably be in this country for 3 maybe 4 out of the 24 months

I never knew such stuff existed. I had to rebuild the engine from my VW Corrado this year due to corrosion in one of the bores following its winter lay up last year.

Would you recommend any particular brand?

Quicksilver stuff is what i use

Ta chuck, I'll get some ordered.

Spray it in the air intake until it stalls and a bit down the bores

I don't think you need to put it on blocks. Modern tyre materials are not permanently damaged by a flat spot, though the ride may be a bit (ie a bit more than usually) bumpy until the tyres warm up and any flat spots disappear.

Putting your car on blocks was what people did during WWII when petrol wasn't easily available, and driving was something that had to wait for the end of the war. And tyres really weren't very good back then. My first car (a 1936 Austin 10) came with tyres with the brand name "Stonehenge". There was surely some kind of message there....

Ideal for use on the rocky road then.

Windscreen wipers off the glass. Doors not fully closed. Drain the wiperwasher water. Take the battery out of the car. Don't put it on the handbrake. First things which pop up in my mind...

Also open the vent flap a little. Spray all rubbers with vaseline.. Putting it on blocks can never harm...

In the past I have inflated the tyres to their maximum pressure (as quoted on the sidewall) to avoid flat spots.
I'm a big fan of spraying clear cavity wax over and risky rusty bits to keep the moisture off (and Vaseline on chrome - not that there's much on a 2cv).
My Corrado will be laid up with the pads & discs removed (they corrode badly), up on blocks with wheels and tyres removed, and inside I'll leave a small electric heater and a dehumidifier. If I had room to put it in the garage I don't think I would do any of this though.