As stated, neither airline flies to Goa.

However there are nonstop charter flights from the UK to Goa, on which you can buy individual seats. It's your choice whether to go for one of these (increasingly they offer a "Business" standard cabin up front), diluting your schedule convenience, standards and points to some degree, or to go for the direct flight avoiding all the transfer issues at Mumbai or elsewhere in the middle of the night, offering a significantly shorter overall journey time, and often notably cheaper.