fair deal required with 2 bed house/mineshaft

onlylookingforaquietlife

looking to sell a 2 bed semi in the midlands, independently valued at £110,000, however, now the bad news, it has a mineshaft 20 metres away from property on the fenceline at the rear of the premises. The mineshaft was last used around 1896, and they say it should be safe after no movement for 100 years! Would i be better looking for a first time buyer, hoping their mortgage provider will allow it or try the buy to let market as whoever bought it could rent it out at £600 a month. I have 8 years £300/month mortgage left on property, so i owe £25 grand on property. Hoping to purchase a property for £200k,ideally would not want to go over a £900 a month mortgage, not in a strong position to purchase new build property and carry on with original, any ideas of how to procede would be apprieciated