Fortunately Conimbriga is accessible by bus from the campsite at Coimbra, though it does involve a little bit of effort. You firstly have to get the 8.00 bus from the campsite into town , you might be able to get the later bus at 8.55 but this might be cutting it fine to catch the 9.30 bus from Coimbra to Conimbriga, though in fact the bus was late. It might say Condeixa on the bus.
At the time of writing (Jan 201) there were two buses a day leaving at 9.30 and 13.25 (check in the tourist office ) and returning at 13.25 and 18.25 respectively which leaves enough time for a visit and a coffee afterwards.
The bus fare was 2.5 euros per person each way and the entrance fee was a very reasonable 4.5 euros, which gives you access to the site and to the museum .The car park is large enough to accommodate motor homes and there was no charge.
It is a stunning site and the main part of which was not excavated until the 1930’s . I would guess that there is a lot more waiting to be discovered.
The mosaics are superb and what is surprising is that some such as in the ‘House of the Swastikas’ remain uncovered.
Though there were a couple of coach parties, we soon lost these and not before very long we were wandering around on ourselves. We were not sure but we wondered if they just came to see the piece de resistance, which was the ‘House of Fountains with its outstanding mosaics and tasteful replica water features. In any case we would suggest that you leave these to last as a fitting climax to your visit , though in fact we went back after visiting the museums and our coffees.
http://conimbriga.pt/english/ruinas.html