Steveking
Another option might be to stay on the East coast - say Newcastle - St Abbs - Perth/Dundee/Glenrothes then Inverness or Oban before crossing to Stornoway.
I instruct up here in North Eastern Scotland but have not yet flown VFR in the Edinburgh / Glasgow "TMA corridors" (did my IR there though!).
You could 'phone Tayside Aviation at Dundee / Glenrothes, or the guys at Cumbernauld or Scottish Aero Club at Perth (Scone). I know that alot of them fly where you are planning.
By the way, RAF Leuchars is just across the water from Dundee and RAF Kinloss & Lossiemouth are just east of Inverness. Leuchars & Lossie will provide LARS during the week.
Enjoy your adventure!
Regards
PS If you are at Stornoway why not visit the other islands like Orkney / Benbecula / Tiree etc!