You've actually found it for sale? I see here it seems
to be offered as a free download (haven't tried it)
http://www.old-games.com/download/6503/rowan-s-battle-of-britainRowan (developer) and Empire (published) are both defunct,
and it's been years since I've seen it offered in an old
sim bundle...
But I see here it seems to be for sale on amazon UK:
http://www.amazon.co.uk/Rowans-Battle-of-Britain-PC/dp/B000050FV1 seems improbably expensive.
Well, I can tell you this much: BoB1 out of the box had serious
problems. It is best run with the last bdg patch, v0.99,
if you can find it out there somewhere.
BoB1 was a DX8 game. BoB2 is DX9, and in Win8, it crashes
with an error in d3dx9.dll, which obviously is part of DX9.
So, it is perhaps possible that the old DX8 game would run
in Win8, but I have no idea. I'm avoiding win8 because BoB2
won't work under it.