You are going to have problems.
As Giacomo Catenazzi says, selling a property to pay for your trip is a bit of a red flag. In fact any large amounts of money suddenly appearing in your account, or the account of someone who is paying for your trip, is going to be a red flag. You have to make sure that your documentation of the sale is rock solid - a legal ...
Whoever you use as a sponsor has to prove that they can afford the commitment. You don’t say how much the overall cost of the proposed short study course will be (travel to UK, course fees, personal spending during the course etc) but however much that is, your sponsor needs to show:
the money is available to you
the spend is proportionate to their income/...
Selling property for a travel is not seen well. You sell properties when you want to emigrate, so break link to home country.
Regular income is much better. And you should try to stress on documents which prove you will return after the course at Oxford (maybe also describing advantages of your course on your career on your home country).
You need a visa to complete an internship in France. The visa you need depends on the duration of the internship. In your case, you need a short term visa since your internship lasts less that 90 days:
This type of visa is generally issued for tourism, business trips or family visits.
It is also issued to persons entering to ...