It really depends.

I know people that got bored to death in Australia because culturally is a wasteland and gladly came back to the stress in London, but some people love nature and the outdoors and lack of culture is not a major inconvenience.

I think that moving to the UK first (that is culturally more akin to some parts of the US than Australia will ever be) you also have the chance to investigate Spain in close quarters. A lot of Brits move to Spain, so there are lots of information, property fairs, etc. in London for people hoping to migrate to Spain.

Now, lets not kid ourselves, London is the most expensive city in the world (or it was until last year), I can't imagine anybody living OK with less than £35000 a year ($70 000), I personally get more than that and all what I have got to show for it is a 2 bedroom flat in one not so good part of town, so beware.

Right now the banking industry is in the doldrums, big employers like Citigroup, Barclays, HSBC and many others are cutting costs like there is no tomorrow and are often outsourcing to India as much work as they can.

I can't say much about the fashion industry, but lets say you will be positioned in one of the most important capitals of the world, in short distance from Paris and Milan, I suppose it is one of the best places to be in that industry (but so is for banking and finance, and alas, times look grim).