Hi J L - it's usually the applicants themselves that arrange the survey with OS and not the conveyancer involved
Notice periods tend to fall into two categories - 65 business days if the land is registered. 15 days if unregistered
The process is set out in PG 5 for you/your conveyancer
The two applications are being processed together so there shouldn't be a need for any second survey as the BL169789 is dealing with already registered land/title
Adverse Possession - Claimed Land - Impact on Timescales · HM Land Registry
BL169789 & BL169507