Hi Guys. My MOT advised the above  on My Mk1 but I’m not really sure where the exact spot will be. Thought I’d try and attack it before it’s considered excessive. Any ideas please?

If it's an advisory, you probably have plenty of time before it becomes a fail (what did the tester actually say?) but, as you say, perhaps better to get it fixed to extend life of vehicle if you want to keep it going until the next corrosion or other issue comes along?

It looks like it is near a structural area i.e important.

So, get an estimate to have it fixed properly (the days of fibreglass resin are long gone).

Or prepare to get rid of it.

Without photos (would like to see), difficult to say but based on experiences from the rot boxes of the 70s that is my initial response.