Sentence 2 sounds better.

SECOND MIGHT BE USED COMMONLY SO GOOD AS THE FIRST ONE

Both are correct, but use sentence two if you're not sure. Use the first sentence if you're tied to a chair and constantly beaten for information.

Both are grammatically correct, but the second sentence is much more commonly used, in my experience.

I'd replace "been to London" by "gone to London". If you do this, both would sound good for me.