I made a special brew a few years ago, I was bored one afternoon and decided to make the strongest beer I could, I used Loads of malt extract and loads of sugar and I just used beer yeast S-04. I got the gravity down to 1020, I was talking to my local micro brewery and told them what I was doing, they told me to add some more sugar and then add some wine yeast, this would bring it down to a FG of 1010, it all worked beautifully, the beer cleared, I let it mature for a few months, it was horrible

, even after a year its was naff, I used it as drain cleaner in the end. Best bet would be give him the £20 and save your malt and sugar for better things.