top-dressing mix when overseeding a lawn?
 

I am planning to overseed my lawn. Looking at previous posts, it seems
that it is recommended to top-dress the lawn when overseeding. Any
recommendations about what the top-dressing should consist
of(loam/sand/peat?), and how much to apply per square metre? Would the
"blended loam" product advertised at
http://www.topsoil.co.uk/compare_soils.asp be suitable for this?

Also, should the top-dressing be applied first, and then the seed, or
the other way around? Or should the seed be mixed with the
top-dressing prior to applying to the lawn?

thanks for any advice on this topic..

Julian