Thanks for your enquiry.
I take it that the property just has one Freehold Land Registry title number, and no Leasehold Land Registry title has been created for the 2 Flats?
Did you obtain planning permission to convert into 2 Flats?
Were you hoping just to carry on paying the existing Mortgage?
I look forward to hearing from you.
Thanks for your reply.
As you obtained a Mortgage on the basis that the property was a single dwelling, you are in effect in breach of your Mortgage if you have now converted the dwelling into 2. (Likewise, if planning permission had been granted for the conversion into 3 flats, I am not 100% sure if you are in breach of this, if you have converted only into 2).
Looking ahead, on the basis that you want to create 2 legal dwellings, you would need to create a Lease for each flat, and register the Leases at the land Registry so that each dwelling has a separate Title Number (merely paying separate Council tax for the 2 flats does not legally solve the problem) and disclose this to your Mortgage Lender.
I hope this assists and sets out the legal position.