After you reach London, type the following during play to go to those locations:
PARIS-"DAY OF RECKONING" | TOKYO-"TRICOLOUR COFFEE SHOP"
NEW YORK---"THE SLYTHER" | SKARO------"D5 GAMMA Z ALPHA"
Type "JAMES BOND AND OLIVER REED WERE NEVER GOOD SINGERS" for invincibility.
Type "TRUE I AM GUILTY OF INTERFERENCE JUST AS YOU ARE GUILTY OF FAILING TO USE YOUR GREAT POWERS" for infinite lives.
Type "ESCAPE SWITCH" for ???.
To get from the caves to the city, kill the Super Dalek and enter the empty room. Now use your grenades to blow away the floor to reveal the way to the city.