Is there a thread to help novices identify a fuel leak issue ? Seems to becoming from the heater channel (it's a 76 so they are at the top of the dash), quite astrongsmell but not losing fuel noticeably. I had a look under the hood, couldn't see any corrosion at the top end of the tank. Thanks all!

If it's a '76 beetle, there is a black plastic expansion tank next to the fuel tank on RHS of car. From this a small plastic hose runs towards driver, across rear of boot at top, down on pass. side, under car, reappears under drivers side: underneath between front of door and rear of guard, then goes to charcoal cannister under rear RHS guard just along the inside of chassis edge. This hose can fracture with age; and there are some joints in it. There are also larger hoses from the expansion tank to the fuel tank, and the filler-tube. Any leaks, vapour or liquid from these areas may be hazardous & smell... if it's from this system, don't fully fill tank until it's reapaired. Petrol can also leak if slopping from the filler cap, or the base of the tank (due to water in it causing rust).

Ive had trouble with the filler tube on later bugs

You should be able to check the top area around the tank, just remove the boot liner and have a good look with a torch if needed; and under the RHS of car, and under rear guard. If the tank is filled to the top, you may see it wet somewhere, and can then get it repaired/replaced as needed. If it's coming out the filler cap, you'll see it wet after cornering (with a full tank too).
The little hoses (black or blue across luggage compartment, and under car - can't recall exactly) might be polythene, or nylon, with clear fuel-resistant PVC sections in the corners under bonnet. Any fuel-resistant hose of the correct size/s should do, but don't use ordinary PVC, it will fracture. Broken/missing hoses under the rear guard at the charcoal cannister are not likely to cause noticable vapour smell in the cabin.
If there are no evident leaks in any of those areas, there may be leaks around the base of the tank: you may need to get it on a hoist to examine that. The hoses there are usually neglected, and must be replaced if hard/cracking/leaking... a minor leak here can come & go, or it can drip onto cover under the master cylinder not drip on the ground. Try to have the tank fairly empty before poking around under there! A garage would drain the tank and replace hose/s as required (the rear hose should be replaced too, if old).
It is possible to have leaks in the tunnel, but if the original steel tubing is in place, this would seem less likely (unless it has been interferred with, or rusted).