According to the TDICLUB - https://tdiclub.com/TDIFAQ/TDiFAQ-3.html

?The heater permits the use of Diesel fuel number 2 down to a temperature of -10F (-24C). ?
?The thicker wax component of the fuel may be blocked by the fuel filter although it can flow through the larger diameter fuel lines. The fuel filter in the Volkswagen TDi is heated to reduce this tendency. ?

and ; I did say the heated tank was an optional extra.

I had never heard of anyone with that optional fuel heater, sounds neat though if for some reason you didn’t already have blended fuel or wanted to run a higher percentage of bio-diesel in winter.

The most common way to get gelled fuel is to fuel up in Florida and drive north ;) We already have Blended diesel fuel here in WI (starts in November) and the peak blend is sometime in January. Any fuel you get in northern states or Canada is pre blended at the station so it won't gel up, otherwise you would have diesel cars, trucks and semi's sitting frozen all over the place. Another reason I recommend purchasing fuel from a commonly used stations, is if for example you buy fuel at a low volume station you could be buying 2 month old diesel that isn't blended.

As far as a heater on my fuel filter, I can assure you there isn't one. I just changed it and there is nothing there but the housing and filter.

I'm familiar with the answers to FAQ on Fred's. I wrote the first set last century. They have been modified by others since then, not quite as much as a wikipedia, but with about as much care to accuracy.
And any part number, or even a partial part number, you can associate with a heated fuel tank for any VWAG product would be greatly welcomed. I have searched extensively through the VW, Audi, Skoda and Seat parts files contained in the ETKa without finding any reference to any sort of heater for any fuel tank. If I can have even a partial part number of any component used in such a heated system I can do a search.
I'll be waiting, but not hopeful.