Thanks Blew, I may take you up on that in the future but for now, the Leak-fix is working and I'm skint!
Glad to report no leaking petrol this morning. Bearing in mind my VX is one of the last made and GC's comment that his VX tank also rusted through, I'm going to keep my eye open for a second hand one. If I find one, I'll get the better tank well and truly sorted before fitting it.
Thanks for all the tips, especially #002 one about the car tank sealer. Wish I'd thought of that before the £17 for petseal and the 2 days of cleaning out the tank.
