Lego's official "Pick a Brick" store? Why would you bother with that when Bricklink has everything you'll ever need. For Aussie stores, shipping can be as low as $3.

I've downloaded Lego Creator on my PC & I've tried planning my builds on that but I just find it easier to search google images for inspiration while simultaneously ordering what I need from a large Bricklink store (when making a big order, I try to stick to Aussie stores otherwise the shipping can get a little pricy).

Then again, I'm planning a MOC Classic Spaceship & I'm currently waiting on 3 orders from Germany containing mostly vintage parts... not cheap... Lol!