Hi Cazcat
I did this tour in May & we only had a local guide for our visit to the Maritime Museum. From there we were on & off the coach for other places of interest, with our tour manager Ricardo providing us with as much information as we could take in, the timings Julia has given you.
There were some of our group who did spend a free day in Lisbon, the local bus takes about an hour, then they used a taxi, timetables I believe they got from the information centre in Ericeira
Regards
Barbara