Any charges to upgrade from DSL to Fibre soon into contract?

Hi

I've just moved house and require a broadband connection, I can get DSL now (2.5mb) and fibre is due to be available in the coming weeks. My cabinet (cab.4) is installed but not yet enabled and other cabinets on my (Minster Thanet) exchange have already gone live and are now AO - I know as I placed an order a month ago for another address on the same exchange but a different cabinet (cab.7).

I've already waited a while for fttc to be enabled on my cabinet but can't really be without a connection for too much longer.

If I sign up to TalkTalk's standard ADSL connection now but then my cab is accepting orders in the coming weeks, will I be faced with any additional charges to upgrade to talk talk's super fast fibre so soon in to my contract? I would assume upgrading would just be the difference for the monthly cost?

Thanks for the help!

James

Ps, I say Talk Talk but may also look at Plusnet.

Cannot comment on those two providers however I do know that BT will allow you to move from an ADSL contract to an FTTC contact without penalty. The only proviso is that the new FTTC contact run from the date of conversion.