OK thanks everyone.
I am constantly reassured by the kindness of people taking the time to help out a random stranger on the internet..

I'm just waiting to see if the new modem firmware being pushed out to virgin customers will improve the rubbish latency I get with my superhub 3...if not fixed then I see no other option but to move to BT.

In case its of any interest:
I called BT a second time on the 16 Feb and talked to a super helpful lady who passed on my lack of address entry in the BT Fibre checker onto Openreach (and their reply was cc'ed to me).
7 working days later I gave Openreach an email nudge to remind them and low and behold a couple of days later my address now appears in the Fibre checker and all is fine.
Have to say I was quite surprised to see it all resolved with so little trouble and extra kudos to the lady at BT who took on the problem and got it resolved.

Just as a matter of interest, how did you manage to chase up openreach, I have got the same problem, post code 4K out last two letters wrong, I have talked to BT so many times I am pulling what�s left of my hair out, they keep saying tat they have contacted OR, but nothing changes. I now had to resort to checking at the green box several times a day to see if I can corner a friendly OR person for advice

Did you ever get a case number from BT or OpenReach?
IIUC OpenReach don't normally deal with members of the public directly but if you have a case number that should help.
Anyway, here is the email that was sent from OR to BT that was copied to me.

"Your case Cxxxxxxx has been created for Postcode xxxx xxx

Thank you for your enquiry. We will respond to your request within seven working days. Please set expectations with your customer accordingly. Please quote reference Cxxxxxxx in any future correspondence.

If you are contacting us about a potential capacity issue, please could you make sure you use the availability checker to ensure that the issue has not been resolved by our in life capacity team.

If, after seven working days, you have had no response please use the escalation information below to escalate further:
1st Level [email protected]
2nd Level � If level 1 has not responded within 1 working day � [removed a personal email address for next stage escalation]
Our normal working hours are Monday to Friday, 8am until 6pm.

Please do not attempt to escalate before the seven working days as we will not be able to deal with your escalation."

After 7 working days I emailed the above email address and got a reply saying "I have contacted another team within Openreach for further investigation into a possible records discrepancy."
Plus a further reply a couple of days later saying that the matter had been resolved....which it has, happy days.
Good luck.