You most certainly can check wine in as luggage. If security or BA try to invoke the "5 litre maximum" rule, you can point out that this only applies to strong alcohol (over 24%). You may have to sign the "limited release", giving up your right to compensation in case of breakage (this depends on the out-station).

Warning: LHR baggage handlers are very likely to smash the wine on arrival, unless it is packed in special polystyrene boxes - usually these are available in wine-producing regions.

Second warning: Don't try to take it through the "nothing to declare" channel on arrival. If you get caught the consequences may be serious. Go through the red channel. Tell them exactly what you have got in the boxes. You will probably have to pay the duty and VAT (UK duty is £1.57 per bottle). If you are lucky you may get let off.

From my professional experience, wine does not deteriorate during air transport as suggested by other posters. Maritime transport, with potentially high temperatures, is much more risky.