BKC engine - help requested locating replacement

Hello,

I am a new member to this forum having recently acquired a 55 plate Octavia 4X4 1.9 tdi. Living in rural Sussex its proved its worth in the leafy lanes and taking the dog to the common,it regularly returned 50 mpg.Sadly at 120,000 the turbo has seized, pressurising the sump leading to engine failure.The car has a full service history.

Can you knowledgeable folk tell me if the replacement engine has to be a BKC or can another coded unit be used (BXE etc?)

I wonder if anybody knows of a suitable engine with turbo for sale UK wide.  

Thanking you for taking the trouble to read this tale of woe, thanking you in anticipation.

Chris