Have just erected a yardmaster tin shed. I need to put a 'sealant' around
the edge of the steel frame base where it sits on the concrete foundation,
to prevent water traveling in under the frame.

I normally get things like sealants from Wickes or Screwfix, but there are a
bewildering array of different sealants available. Would anyone recommend
which would be the one to use in this particular application please?