Not quite so Eng (ret).
It can take a little bit of writing to achieve, but you can do it either way. Last year I PVR'd (50+) and I now work alongside, inter alia, another guy who left slightly before me at (I think) his 44 point.
We have each chosen to do it differently. I have all my allowances taken off my pension, and my pay is then taxed at whatever marginal rates apply. (And my pension is certainly NOT my main income!!) My colleague does it contrariwise, with his allowances taken from his pay, and marginal rates applied to pension. Only took a coupla 'phonecalls/letters in each case.
And of course, overall it makes no difference - you get paid £xK per year from various sources, so IR deducts £yK in tax. Net result in both cases £(x-y)K in pocket, so doesn't matter (unless herindoors sees pay slips!)
But you do have to tell them! £500 a month might hurt, but it seems to me to be better than an annual £6K demand......