On 2008-05-18 23:09:04 +0100, AmyGG said:

I am looking for a long tv unit that I can put my tv and fish tank on.
I think the weights are approx 40-50kg and 70-80 kg respectively.

I have found one particular item I like:
http://dwell.co.uk/product.php?prod=102414

However, the total weight is over the maximum load advertised. Aside
from the water/electricity danger (which I will be extra careful
about) is it ok to have my items 'slightly' over the maximum load?

This isn't slightly over the 100kg limit of the TV bench - 130kg is
quite a bit over.

Ask the manufacturer and see whether they say that it's OK to exceed
their specification.

Write to your home contents insurer and ask them for confirmation as well.