Due diligence, then the funding structure, then a purchase agreement drafted with the requirements in mind, then commitment of funds, then the application. Steps taken out of order are the usual cause of a file that cannot be repaired.
Every irreversible step needs a condition attached
Hypothetical example: the couple sign, release the deposit and give notice on their Coalhurst commitments before anyone has looked at the loan security or the escrow conditions. Reverse that. Start with the shop's records, licences and lease.
Settle the loan structure and read the security clauses. Have the purchase agreement drafted knowing that funds must be irrevocably committed and at risk, and that the buyers must be able to develop and direct the business. Then commit, then apply, allowing for the responsible agency's current processing times, which are published and change.
Neither spouse should resign, relocate the household or begin working in the shop before a status permitting that work exists. Keep the Coalhurst arrangements viable longer than the optimistic timeline suggests.