Just done my tank with this:
http://www.ebay.co.uk/itm/FLOWLINER-ARMOUR-COAT-PETROL-TANK-LINER-ETHANOL-PROOF-/200628149745?pt=UK_Motorcycle_Parts&hash=item2eb65e9df1
..easy to apply and seems to coat nicwely but yet to test with petrol! Will be using with good quality petrol like Shell V Power...although not many Shell stations in the parts!