You should be able to make an English Bitter of some sort out of those two cans.
+1 for getting some steeping grains. A bit of crystal always comes in handy. (just buy a kilo, use about 150-200g & save the rest for future brews)
I've never used Gold Cluster but googling it shows it as a bittering hop for aussie bitters/lagers.
I'd say use that as your bittering hop, and use the fuggles for flavour & aroma.
Leave the dex for priming IMO
+1 for preferring windsor over S04, but I've made some great beers with S04 so go for it.
Have a looksy round on the net for recipes using those cans, play around, substitute ingredients and take notes.