Steps to obtain license to alter for structural changes in leasehold property

[Ewa]

I own a 2-bed ground floor flat (in a purpose built with four flats, so there is only one flat above me and one next to me) and plan renovations that would involve making some structural changes, although not removing entire walls: partially removing a wall in bedroom to carve out space for sliding doors that would turn a wall-long storage into a built-in wardrobe and partially removing wall between the lounge and the hall. I have already instructed a structural engineer who has identified the walls as being structural and possibly load-bearing. I have been communicating with the freeholder (Alan Mattey Group) who have already sent me the draft license to alter, although they haven't seen or requested to see yet the technical documentation. The freeholder confirmed that, in the case of structural works, they'd need to refer to their own structural engineer. My lease allows changes to the layout pending consent that can't be unreasonably withheld. My understanding is that I will also need to seek the council's building control approval and potentially a party wall agreement or notice. I'd be grateful for some advice on the process and whether it would be worth me instructing a surveyor (would they help with the entire process) and/or a solicitor. I find it odd that the freeholder has already sent me the draft license without requesting to see the technical documentation first. Thank you.