IMHO the roof is a bit of a mess. Looks like something has changed at some time and the end of the purlin has become unsupported. Also possibly concrete tiles replaced original slates. As woody says, I think a brace support under the purlin down on to the wall would be a good move, but will draw attention. Personally, I would just plead ignorance and try and sell. Buyers prerogative to survey or not.
Years ago we nearly bought a house which turned out to have horrendous structural roof issues, picked up in our survey (big dormer bungalow with a "T" extension where the purlin joint loads fed down through a wardrobe centrepost into gnd floor ceiling joists...). It was a repo, and eventually the selling bank accepted an offer that was about 40% of the original asking price. In the end though, we backed out - it would have been a building site for a very long time and significant other didn't want the hassle. If we hadn't surveyed, we would never have known.