A neighbour of mine used the Tampere - Stansted flight once, some years ago, to go to an Arsenal match (he's a fan).
As I recall it left quite late and he found it difficult arriving very late at night.
To get to Tampere (Helsinki) airport, as Ryanair described it, takes a bit of time.
It is about 200km from Helsinki!
Nowadays Norwegian flies to Gatwick and the non BA/AY customers use that.
Norwegian go from Helsinki main airport, twice per day and at roughly the same time as BA.
Norwegian may go to other UK destinations as do Finnair.