Well for Bruges you've just got to walk all around the city inside of the walls, taking in a few views from/or bridges into the city centre itself. It's one of those places where you just get lost and eventually find where you are, rather than planning out an itinerary.
Personally, I'd skip Bristol and Aberystwyth (you don't want to be picking up any local accents
), and spend more time in Iceland outside of Reykjavik.
Alternatively if you're travelling around Wales you have some great seascapes and 12th/13th century castles to explore and photography (Conway, Carnarvon, Caerphilly etc)
With London, you have the usual touristy subjects (Tower Bridge, Tower of London, St Pauls Cathedral, Trafalgar Square, Whitehall, Downing Street, Parliament Square, London Eye)
The order I've placed them in there is a good walk, but in one line from Tower Hill tube station - a great early Sunday morning walk.
You then have Regent Street, Picadilly Circus, Oxford Street, Covent Garden which are all very close to each other.
Don't forget the parks - plenty to visit, and for gothic architecture the Natural History Museum is good.
There's loads to do - I'm sure you'll be flooded with suggestions...