This is a limited offer on Groupon and is valid Mon-Thur but if you don't fancy signing up there are a couple of offers on the Three Locks website although not as cheap.
The course is close to Milton Keynes and Leighton Buzzard (about 30 miles from Chesfield). I played it a couple of years ago and thought it was very nice. It's rated 4.14 out of 5 on Golfshake. Well worth making the trip particularly at this price.