The CTW scheme is a perk from the employer, and providing you ride the bike at some point then the government have achieved their aim of getting more people fit. Under the scheme you are only leasing the bike for the first year normally and then your employer will sell it to you for a laughably small sum.
My employer has been running the scheme for three years now and there have been no checks at all, and much like the OP I work for a large corporate; if checks were necessary or requested by the taxman/government then they would definitely do them. I ummed and ahhhed for a while myself, but in short I would not worry about it.