The tokens for the above 2 cards should remain on the field even if the monsters were destroyed in the process. e.g. if they were crashed to an identical attack monster.
Lord British Spacefighter does not give the option to make a further attack after it has made multiple attacks ie. after destroying a 3rd monster in a row, the only further option is to destroy a set card, or to make an option token. Not make a further attack.
Regards