Woodvale and Lossie - make sure you have Crown Indemnity document with you, or expect a surcharge. Telephone on the day to check that your PPR will be honoured (things change quickly).
Prestwick - mandatory handling so try and make an arrangement with the club beforehand and tell ATC. The club was closed when I diverted in and handling was about £90 (landing fee was refunded due to weather divert).
Oban - Paul Keegan who runs the fuel operation is the local weather expert. If conditions are changeable (i.e. most of the time) he will predict a window for the short run to Glenforsa.
Glenforsa - the airfield slopes down to the Sound of Mull. Land and taxi on the 'uphill' side as it can get boggy on the 'wet' side, even though the grass looks inviting.
Skye - low level flight along the cliffs on the eastern side of the island highly recommended.
Plockton - walk into the village for lunch (20 minutes).
Carlisle - consider Kirkbride as a lower cost, GA friendly alternative.
Sounds like a great trip. Take a camera!