How to secure small building plot within garden grounds

NeilT1314

Hello folks....I'm a recently retired tradesperson , with a desire to construct a small " Coachhouse or Converted Stable " 2 bedroom type of retirement home in my existing garden grounds...not far from Stirling/ falkirk...I've previously been granted outline planning for a large 5 bed dwelling ...but time has marched on as the saying goes...& a nice wee cottage is probably more suitable now....the help or advice that I seek is how to go about legally securing said building plot { I already possess scaled plot drawings } ,without getting unduly weighed down by fees for " legals " for doing admin & forms that could be possibly done by myself ,as I've received a lot of conflicting advice mostly the sort that is geared towards " fee garnering " it seems......some thing I would rather keep to a minimum ...if at all possible.
I would be extremely grateful to any forum members out there who may be able to give any advices drawn through their own experiences .....
Many Thanks.