I don't know but quite possibly not - if they're expecting a female and a male turns up he may be refused boarding onto whatever it is. I'd get it changed pronto.
what sort of tickets? If its train or coach tickets to a uk destination i doubt it would matter thayt much. If its festival tickets it will matter. Why not just give whoever sent you them a ring to ask them
Not worth taking the risk of arriving at the airport and being refused, get them changed. The details on ticket have to match name on passport, yes only minor detail but someone is bound to say something, best to do it before, same thing happened to me spelt wrong on tickets, had to send mine to airport as no time to post, put extra stress on what should be fun time worrying if they would be there ok, never again.