Walking through two taxonomy vocabularies with Views [Solved]

Have looked through the Forum and the Docs but haven't spotted what I'm after so am really hoping for a steer in the right direction.

I am developing a site where the main content type Establishment has two Taxonomies; Category and City.

A Category could be restaurant/bar/cinema/etc and City speaks for itself - New Terms can be added to either taxonomy at any time by the user.

I have been able to create a View which has the capability to show:

i) All the Nodes for one Category, and
ii) All the Nodes for one City.

I can even type multiple taxonomy terms into the URL and show all the Restaurants in London (for example) via the same view, e.g. URL = taxonomy/term/2,5

...This is what I want to be able to do, but I want users to be able to get to any existing Node intersection of Category and City taxonomy usage 'without typing the URL in', and it needs to be dynamic as new taxonomy terms can appear at any time, e.g. no menus with fixed URLs behind them.

More than happy to do this in two steps, e.g. step one go to all London Establishments and then step two 'narrow' to all London Restaurants.

I have a feeling after step one (which I can do now) if I could get hold of the Id of the Current Taxonomy term I could feed it into a Field Link in the View, e.g. node's Field would link to taxonomy/term/[current_term_id_from_url],[node's_term_id]

Not much of a PHP programmer, but prepared to have a go if only option.

Would really appreciate some guidance as I think I'm out of ideas, and taxonomy/menu modules.