Yes ,I have I went on a organised coach trip ,where we went around and viewed, think its operating soon for those who want to walk around the part they say and the grounds at the back .
You go through a security check,which involves removing things like money related items and thing such as your keys ,before you proceeded to do your tour ,armed with a guide book at a price ,and shop area in the grounds selling items related to the palace.
The group i was with the organiser, did it as deal on the coach trip ,after the walk around the palace we went to a hotel in the Strand and had a carvery roast dinner after and some free time before getting back on the coach home .
Mick