By plane, train or automobile?

I have a conundrum. Well it's not really a conundrum but more of a dilemma. And when I mean a dilemma, it's a First World Problem.

I have planned to do a small tour of the southern United Kingdom some time in the middle of 2015. Being the obsessive compulsive person, I have already mapped out my trip in advance. After landing at Heathrow, I embark to Newbury to see a friend, followed by stops at Stonehenge, Bath, Cardiff, Abergavenny (to take in the majesty that is the Brecon Beacons), Oxford before finally seeing another friend in Cambridge.  That will be six towns (UK doesn't really have cities) in eight days.

The quandary here is my method of transport. I didn't have this problem when travelling in USA earlier this year. With the American public transport system being so poor and automobile travel being so popular in the United States, choosing a road trip was an absolute no-brainer. In UK the railway system is considerably better to make travelling by train a viable option, although a bit expensive. Also adding to the equation is that renting a manual transmission car is cheaper than automatic in UK, and I haven't driven manual since I passed my driving test over ten years ago.

So the logical part of me, researched the problem and come up with the pros and cons of travelling by car or by train

Pros of travelling by car / cons of travelling by train
1. The journey time will be quicker - 10 hours 30 minutes compared to 12 hours 31 minutes by train. And the car journey time is including a trip to the Stonehenge, which is not feasible if I go throughout my whole journey by train. If I was going to include Stonehenge in my train journey, I would need to travel to Salisbury and get a bus from there to go to Stonehenge, and that is not something I want to do.
2. I have more freedom of where I can go and I am not limited by public transport. That would definitely help for certain places where public transport is not great, such as Abergavenny and going to St Fagans Castle in Cardiff.
3. I am not limited to train timetables. I can leave and arrive by car whenever I want.
4. I can select hotels or bed & breakfasts in the outskirts of town If I was travelling by train, I would have to select accommodation near the train stations or near the city centre.

Cons of travelling by car / pros of travelling by train
1. Cost: the cheapest price for an automatic car for the dates I have selected is £190.83. That figure doesn't include additional costs like petrol and parking. If I was going by train, it would be £159.80.
2. I would need to get a satnav for the car. If I get the system through the car rental company, it's going to cost £100. So the car rental companies can F.R.O. A better option is to get a prepaid SIM card for my smartphone and use Google Maps or Waze to navigate. At least that is a cheaper option of about £10 and I was going to buy a SIM card anyway.
3. I need to find hotels or bed & breakfasts with car parks. If the parking is free, that would be even better.
4. With a train journey, I don't have to drive. I can sit down and enjoy the view. I can take a lunch on to the carriage. I can catch up on my sleep on a train. When I drove in USA, I got sick of driving at the final days of my trip. I didn't note how many kilometres I drove when I returned the car in San Francisco but I've gone back and calculated I drove a minimum of 2400 km in eight days. For the same time period, I will be driving about 800 km. Not so bad this time but I still would like to keep my driving experience to a minimum.

My problem is basically convenience over cost. If I was stretching this journey out over a longer period, I would consider going by train. With the tight schedule I'm having, I think I might opt to travel by car.