j0hn, good to know that you managed to get login details first time around...however as you rightly state its down to pot luck. I think when people call them up they've got to accept that they might have to deal with a pig headed script reader whose vocabulary might include a lot of "'compu'er says no" (ala Carol Beer from Little Britain) and the only way forward might be to call again and hope for a more sympathetic/understanding agent.
As to why Vodafone FTTC isn't available at your address even though they've LLU'd your exchange where your fibre terminates at, some possible explanations:
1) Your FTTC cabinet might be full so with many ISPs you cannot place an order until a port becomes free again - even if you are already on a vdsl2 service. What does the BT checker say for your tel number / address ? (note: address option is down at present)
https://www.dslchecker.bt.com/2) Vodafone may not have yet connected the Openreach VDSL2 fibre links to their MSAN equipment at the exchange using a special cable. LLU operators normally do this within a few weeks of an exchange going live for FTTC connections, however it can take many months or they may even decide not to offer FTTC services if they feel they won't be getting a good return on their investment. I'm sure the cable they use at the exchange is not a 7dayshop 99p jobbie
3) Vodafone's database may not be up to date wrt FTTC services at your address/exchange footprint. You would need to speak to VF level 2 tech support, definitely not their sales staff in order to find out more.
EDIT: It appears other current FTTC users are having the same issue so once BT/Openreach update their availability checker, VF database should update accordingly.
http://forums.thinkbroadband.com/general/4508643-address-checker.html#Post4508688