I also used Tank Care Products of Norwich and found them to be very helpful with advice on how to remove and replace the old sealant. The ethanol had turned the Pet-Seal in my tank into a gloopy white sludge which constantly blocked the carb. Their remover and ethanol resistant tank sealer were excellent. Protect your paintwork though because the remover is powerful stuff and the fumes will strip paint from the tank if they come into contact with each other. Don't ask me how I know this - the memory is still too painful to bear!
1939 600 OHV 4F, 1956 MKII Square Four, a Healey, 1939 OH 250, 1939 OG 250 plus a couple of OG250 projects, 1920 Ariel V twin project and a variety of lesser makes