Should I get the work done before I put my house on the market or get the prospective purchasers to do it?

We received this letter from a lady in Cheshire dated 19th November 2012 whose thatched property had been on the market for over 2 years.

Many thanks for your help getting the roof repaired for me – an excellent job – it just proves the point when selling a property making the outside appearance look good works.  My house sold a couple of weeks later . . . everyone passed comment on how good the roof looked” (Mrs Dolman, Whitegate).