I'm shuddering at some of the names mentioned here
For port, alas I can't comment on the cheaper stuff. Who ever mentioned vintage (or a single di quinta) is sending you in the wrong financial direction though Tescos Finest is only around £15 a bottle and quite decent. Vintage port only lasts just over 3 days once opened (and decanted).
Whether you go for a tawny or a ruby style port (ruby style = vintage, single di quinta, LBV, and ruby) depends on your tastes. For cooking you want a ruby. The suggestion of Cockburns is a fair one, though for ruby (as opposed to a ruby style) you won't go far wrong with all the big names. Personally I think you'd be better off with an LBV (which does not need decanting from what I remember (though that's going back a fair few years)).
Brandy is more down to taste. Cognac and Armagnac are the two main ones. The latter is harder to get hold of in this country and tends to be cheaper, though in France it can attract a more 'elitist' crowd. Hine, Hennesey and Remy Martin are the better main stream labels to go for. Courvoisier and Martel are considered to be cheap and poorer quality. Don't go for generic French brandy.
For non French there's only one really worth considering - Asbach. It's a decent alternative and cheaper than the French power houses (though in many respects you do get what you pay for).
With Cognac the stars and letters indicate length of time in the barrel, the longer obviously the better. The order is *** - VS - VSOP - XO above which you can find then find types with names like Crystal and Ancestral Reserve. Armagnac tends to just give barrel age instead, though some of the more common ones (such as Janneau) use Cognac descriptors.
