Missed the full cab post.

But (sit down please) would agree with BatBoy and cancel the migration, either renegotiate with Sky (might be able to push them to £10/m plus line rental if you sign up for 12 months) or wait it out until cabinet is out of capacity state. If I recall I waited 10-12 weeks for that - hopefully when I do next years experimental move there won't be a capacity issue.

In reply to a post by BatBoy:

Personally, I would cancel the migration until the cab is showing availability, and try some renegotiation with Sky instead.

I agree I would 100% not proceed with this migration. My experience is that the port will be lost as well. Due to a lack of available ports I expect the user to either be stuck on ADSL for a long time or to have no broadband what-so-ever as they are in the waiting list. Either is not pretty. Once you lose the port you are at the bottom of the waiting list.

Just been in touch with BT again, it appears that the problem stems from my property being still down on their system as the original plot No instead of the official post office address number, which I thought I had previously sorted out through SKY.
The operator is getting back to me tomorrow to see what they can do for me.

In reply to a post by krustykrab:

Just been in touch with BT again, it appears that the problem stems from my property being still down on their system as the original plot No instead of the official post office address number, which I thought I had previously sorted out through SKY.
The operator is getting back to me tomorrow to see what they can do for me.

Fingers crossed for you, all I can say is when migrations go bad they usually go real bad ie no connectivity for a while. You might be jumping into the frying pan here and chances are you can negotiate a decent deal with Sky retentions which is likely to be the same or better than BTs offer without the risk. Where my broadband is concerned I am risk averse ie I cannot live without it so I would be seriously considering whether to proceed with this migration.

You have multiple issues here:
1) Address not correct on BTs system
2) Waiting list at cabinet
3) BT to-date have failed to migrate you normally ie seamless broadband and phone at once (further suggesting an issue down the line)

All of the 3 things above should be raising some alarm bells. Certainly just number 1 alone has caused significant delays in many cases. When we factor in the waiting list as well it becomes too risky for me. I feel here there is more chance of it going wrong than going right, especially with a mass market provider such as BT.

Have now cancelled the order.
Does not inspire any confidence when they were sending mail correspondence regarding a new line installation which was not required to the incorrect address (old plot number).
Strange thing is when I rang them they confirmed that there is a current telephone line connected to my correct postal address yet this does not bring up any result on the BT wholesale checker.
I really need to get my property sorted out correctly in the openreach database before trying to migrate at any time in the future.
Can anyone suggest a way forward, have tried to do this before by contacting SKY but it does not appear to have been successful

A Sky phone line will not normally show up in the BT Wholesale dbs. Sky phone lines in nearly all cases being MPF LLU which don't involve BT Wholesale. The BT Wholesale phone line dbs being a subset of that of BT Openreach which should include all lines.

So is there anything I can do to ensure a trouble free migration in the future

Honestly the most likely route is going to be BT sort it out. I would deal with that bridge when it comes to it. I hope sky offered you a good deal, ensure to call cancellations and speak with retentions. Obviously do not cancel, but the best offers to be had sit with that team.

Just to update I was looking into re negotiating with SKY then discovered that my address is now registering correctly on BT database and the cabinet has come off of waiting list to FTTC available.
Had another go at ordering infinity 1 and it all appears to be proccessing correctly this time (including £140 tracked through quidco) hopefully it all changes over smoothly this time.

Great stuff! Keep us posted.