thank you all for the prompt and expert replies!!!

I guess I will still stick to the two spots I've mentioned...don't have the daring yet to explore London off the beaten track yet

What I'm aiming to buy hmm...not much of an aim actually lol just wanna avoid overly generic stuff (keep calm and carry on, union jack themed etc) but more unique specialities. That's why I wanna visit both but am not sure if time allows...

Arriving at KGX noon-ish, and if I take up ppp909 suggestion of doing both (does time really allow? 10pm flight), where can I store my luggage? I checked out the left luggage service links, but it's not like that I put them at St. Pancras and travel back to pick my suitcase up when I leave right...

And I won't mind walking, yet it's my first time in London (go figure), so that's why I'm so confused about the various stations that seem right next to each other yet on google maps (sorry) they tell a different story.

anyway thanks for the patience