whats wrong with underseal?

Something like red oxide is probably a good bet, or some other high metal content paint.  Underseal is awful stuff, its ok until it gets perforated, then the rust starts and moves on from there.  You would be advised to put a coat of something like red oxide, then once its dry put Schutts over the top of it.  Double the hassle, but you will probably rust 1st.

ahhh... you deffo need some flexible rubber paint stuff then..... just dont know where you can get any

edit: a quick google gave me.....

http://www.firwood.co.uk/webapp/wcs/stores/servlet/ProductDisplay

http://www.frost.co.uk/productList.asp?catID=28&frostCat=Rust

http://www.nwepaints.co.uk/acatalog/Chlorinated_Rubber___Pool_Paint.html

http://www.plastidip.co.uk/index2.cfm?page=productIndex

and theres loads more... http://www.google.co.uk/search?hl=en&q=rubber+paint&meta=cr%3DcountryUK%7CcountryGB

swimming pool paint sounds just about perfect for what you want
its a bit pricey at £50 a tin... now sure how many you would need ? you want it on nice and thick

http://www.nvf.co.uk/Paint.htm

that stuff is what they paint on Galvanised railings and the like.  Its got a high Vinyl content, and sticks to a prepared surface very well.  Beats the crap out of hammerite because rather than flake when it gets banged it flexes.  

Go down to the nearest Wilkinsons and have a look at their roofing stuff, might have some underseal paint too.

Underseal is useless unless you put some form of backing pain on it though.  As soon as you get a slight split in the damned stuff it starts to rust, and by the time the rust is visible its too late to do anything about it.

Went for some roofing paint that is sold in B&Q in the end.
Its called Thompsons Roof Seal (stated no priming! & was £20) and is a highly flexible water based acrylic coating.
In conclusion it doesnt stick as well as i hoped to the VW paint work but i think when i get all the insulation and vapour barrier in on top, it should be ok. I am worried about the floor tho! Although i have a VW mat to cover it and will add vapour barrier plastic to get the best i can.
The stuff will stay on fine but seems to come off pretty easily if it is scratched. It lied on the tin


I might start a work log on this if i get time as its becoming a bit of a beast. Pictures incoming knighty

Says 6 hrs on the tin but i left it overnight. I have covered the entire floor and sides now. The plan is to leave it for perhaps the rest of the week.