Did the British employ a reasonable strategy in "Bismarck"?
Given the assumptions they were working under, yes.  Those assumptions proved incorrect,  but in real life you don't get to check the rulebook and the numbers on the counters before you decide on a strategy.  The assumptions, roughly speaking, were:

Crippling the Bismarck was as good as sinking it.  This is roughly the equivalent of the victory conditions; losing a battleship was acceptable provided that the German ship was damaged enough to be finished off by reserve forces, aircraft, or submarines, and the British remained in contact so those forces could reach her.  One battleship obviously could not guarantee this, but two or more probably could, assuming that

One battleship is much like another.  That's obviously the heart of the strategy; how many ships are necessary in a group? To be completely safe, you would need all your ships in one group, which would mean you would never actually have a battle.  The assumption that any two battleships would be enough to destroy any one was not unreasonable, given that a series of treaties in the 1930s had ensured that every battleship should be on the same displacement, and so should be of roughly equal ability. Actually, the Germans had built a heavier ship than allowed, and lied about it; but that isn't something you can ask an Admiral to decide, and in any case the final showdown, between a Bismarck with steering damage but unimpaired fighting ability and two normal British battleships, ended in success.  The unexamined, and flawed, assumption here was that

One British capital ship is much like another.  The Prince of Wales was admittedly not the best-trained ship in the fleet, (she went to sea with dockyard workers still working on the turrets), so the Admiralty teamed her with the 'Mighty Hood', heaviest and most prestigious ship in the Navy.  A good plan, except that Hood wasn't a battleship at all. There was a clear distinction when Hood was built between 'Dreadnought battleships' and 'battlecruisers'; the latter, the same size as the former, had better engines but less armour, in order to support friendly cruisers and catch raiders.  'Jane's Fighting Ships' (1908 edition I think) welcomed the idea, but warned of the danger that battlecruisers would be treated as battleships and asked to face enemy battleships, which they would not be able to do.  Sadly, this proved prophetic.

If you're asking purely in game terms, the obvious answer is that each hunting group needs to be strong enough to sink or cripple the Bismarck while losing no more than one capital ship, but no stronger (since you need as many groups as possible).  How many ships is that?; you're the player, you tell me.