Hi
Surely there is no need to seal a table with teak oil when it's brand
new ?

Oh yes there is! Teak (if your table really is teak) withstands rot very
well, but that doesn't mean it will look pretty while it does so.

Has anyone else experienced this before ? Do homebase use a poor
quality teak ?

Everybody uses 'poor quality teak' or a similar hardwood. That's how we
plebs can afford hardwood garden furniture. If you bought a table made from
'top quality teak' it would cost thousands.

Dave