We are looking at a rail and hike trip, that goes from Glasgow and ends in Mallaig. Is it feasible to take train or bus from there to Inverness area for more hiking and spend 4 or 5 days without a car, then fly to London from Inverness? We have been to the Edinburgh area a couple of times so that is not part of our plan this time. We have driven on the left side for several trips, but would not mind getting along without one on this trip.
Scotland travel planner: http://www.travelinescotland.com/
You can get to the start of the West Highland Way at Milngavie from Glasgow by local bus.
West Highland Train Line serves Fort William - Mallaig and is scenic.
On reaching Mallaig you would need to backtrack to Fort William by train. Then transfer to the Stagecoach Highland bus from Fort William to Inverness.
National Rail Map
I really think that you need to get a car. If you are comfortable driving in the UK, you need to accept that in the highlands your train options are limited and so you must rely on buses. If you want to spend you holiday waiting for a bus and backtracking to catch a bus, then that's your choice. But personally if you can afford to rent a car, why wouldn't you? You are spending so much money already on your vacation, it just does not make sense to me to try and rely on public transit in an area where it is not very good.
I am a big fan of public transit. I ride 5 days a week to work and on the weekends to get around. i almost took my Christmas tree home on a bus. So, it's not that I am anti train, or anti bus or any public transit. But when you have X number of days on a holiday, you need to think about the time that you spend in transit and being dictated to by bus schedules.
If you are nervous about driving or are a poor driver, then that's a totally different story. You will need to deal with limited public transit.
I enjoy the freedom to roam without having a car to deal with on point to point walking tours. If you have a car, you are either constrained to loop routes, or have to make provisions to get back to the start of a point to point walk. An alternative is to have non-walkers travel with you and charge them with the responsibility of moving the car between the track's start and end.
Having a car to serve a point to point walk feels a bit like the fox, chicken and sack of grain across the river problem. It can be a lot more work and effort than using transit alternatives.
I too am trying to do the Highlands without a car. I am going from Edinburgh to Oban, Isle of Iona, Glencoe, Skye, Inverness then back to Edinburgh in May 2017. My pickle is getting from Glencoe to Skye on a Sunday. One of my priorities is to take the train from Fort Williams to Mallaig. I found out I cannot go direct to Portree on Skye as the bus does not run on Sunday. I am going to make the train ride to Mallaig a round trip and then try to catch a bus up to Inverness. Another Rick Steve's travel post suggested I sign up for a tour from Inverness to Skye and then just get off in Portree and not return to Inverness. So that is what the plan is right now. I will be traveling alone so do not want the hassle of driving/navigating by myself. Although trying to get everywhere using public transit may not be a walk in the park. I will let you know how it goes. I had one world traveler tell me they just hire a driver in the Highlands. I had never heard of that and they have a bigger budget then I do but I would love any input from anyone regarding that possibility.
Getting a car, which will mean doubling back if hiking, is probably the best idea. The area of Highland Council is about the same as Belgium, but with about eleven million fewer people.
And that lack of eleven million will have an effect on the public transport. Sunday services I would never trust if I can even if they are scheduled.
Just for your state of mind, I would say if you can, hire a car.