I'm on the same exchange. It's only very recently (beginning of December 2012) gone live - my cabinet (P13) was in the first wave, but I'm in a completely different direction from the exchange (almost due east, on a 1980s housing estate with fairly decent underground ducting). I've no idea whether BT Openreach have rolled out to the PCPs beyond Flitwick town yet.
The FTTC twin for my cabinet was on the ground for well over six months before it went live - and it should have been one of the easier ones. Power came from a street light a few metres away, the FTTC cabinet is just a few metres away from the PCP, and I don't believe there were any ducting problems on this side of town.
I hadn't realised Pulloxhill is on the Flitwick exchange. That's fortunate for you, because it seems unlikely that any of the surrounding exchanges (including Ampthill and Silsoe) will be in the commercial roll-out.
BT Retail have been marketing Infinity fairly aggressively to me - I had two phone calls before Christmas and a letter today. I'd placed my order to upgrade my Zen ADSL service to FTTC before I got the first call from BT. The installation should take place on Tuesday morning (8 January).
If your phone service is from BT Wholesale (i.e. from BT Retail or one of the service providers using WLR), the 'by number' version of the BT Wholesale availability checker
should indicate whether you can order FTTC. If you're not sure whether your line is from BT Wholesale, try anyway - the worst that can happen is it doesn't recognise you.
If that checker doesn't work 'by number', try 'by address' - it's indicating FTTC is already available to my address and, if I've correctly identified an address on your street from the postcode, to your street too. The 'by postcode' option is not showing FTTC availability for my street, so I'd regard that as useless.