There is currently an offer online at Boots where you get a free Revlon ColorBurst Matte Balm (normally £7.99) when you spend £10.
However there's a glitch where you get one for free (in the shade called "Unapologetic") with ANY Revlon purchase, just add the lip crayon (Revlon ColorBurst Matte Balm in "Unapologetic") first, and then any other Revlon item, and the lip crayon becomes free. There are eyeshadows (Revlon ColorStay ShadowLinks) for £2.99, which means you could get both the lip crayon and eye shadow for £2.99 in total. Some of the eye shadow shades are out of stock, but there is obviously a lot of Revlon items this offer works with!
NOTE it only works with the shade "Unapologetic" (kind of a bright light/medium pink shade). Add this to the bag first.
Free click&collect to store as well. :)