6% being the going rate for realtors (split between buyer and seller) a £500K home would of course net £30k for the realtors involved (comes out of the seller's haul).
The difference being there aren't 'buying' and 'selling' real estate agents in the UK, just ones representing the sellers. A buyer just approaches a bunch of agents asking what is on their books (or looks on RightMove).
And 1.5% is a ridiculously high amount for what they actually do. Strike will list you on rightmove for free, and do photos etc for about £800. Purplebricks in the £1k range (£1300?).
And 6%? Try ~1.5%