I think your biggest challenge is going to be to convince people to pay such a premium to save the 10 minutes they would need to make a coffee (of more or less equivalent quality) with a French press. I'm a coffee lover but I am not a coffee snob, so I don't dismiss your product based on it being instant coffee, but £60 a month is enough to cover a new French press every month plus the best beans that my local coffee shop sells and still have enough money left to go to the local café every now and then when too lazy to go out. And that's only if you don't like Nespresso-type coffee, in which case after an initial investment of 50-ish pounds for the basic machine, £60 a month is enough to buy me 150+ cups of coffee a month.

And this is just the price for 32 cups of coffee a month, which is at most 1/5 of my normal consumption.