Splitting a title

Hello
I own a freehold property which is comprised of a ground floor retail premises and first floor one bedroom flat. The flat and shop are not connected and have their own separate entrance/exit.  I wish to split the title of the property so that we hold the flat and shop as two separate titles.  When we have approached a solicitor they advised that as a commercial lease is already registered for the retail shop and the property is a single building over two storeys it is unlikley that we can do this.  We would like to develop the retail premises into a flat and then extend the 1st floor flat to make it bigger.  We thought that is the titles were split it may make planning permission easier and so that we have the option to sell each flat separately once developed, or perhaps sell one and keep one.  Would it be possible for us to split the title once the current commercial lease expires or more likely to be possible if there was not a commercial lease already registered?

Hello - how the property is registered has very little impact on the planning process so the need to 'split' it now may not exist
If there's a mix of freehold and leasehold now then any split is likely to be refused except in exceptional circumstances.
I would suggest pursuing/checking the planning requirements first as the split is likely to occur naturally when the new property is sold for example

Hello - thank you for the reply Adam. We shall instead pursue the planning application first.