The Joys of Life Country Park offers accessible B&B accommodation and is a Caravan Club 5-pitch site as well. They might well allow you to park here if asked: http://www.thejoysoflife.co.uk/
Their main guests are people coming from all over the country to take the (currently) fastest zip wire in the world and the longest in Europe. They accept people with certain disabilities: http://www.zipworld.co.uk
The ramble takes you past the slate tips produced when Bethesda was the slate capital of the world before the views open up to the glaciated Nant Ffrancon Valley. Ahead you will see some of the peaks of Snowdonia in all their glory as the track climbs steadily upwards.
Then the track steepens. As you ascend, keep a good eye on your battery, ensuring you have enough for the return journey. If you do make it to the top there is a cafe and toilets waiting for you.
Much of the track is on a very quiet public road so recovery is possible if you do get into difficulty!
Remember - the route distance is only shown one-way. It is 11 miles in total