Ok guys, my experiences of travelling to and from the track were mixed,
Saturday
I had bought my train tickets online via the TrenItalia app (2.5 euros each way) got to the station in plenty of time, and headed to the platform. Train to Misano Adriatico arrived on time, 15 minute journey and I was there. Followed the crowd out of the staion, turned right then first left, which took us to a road train, which was 7 euros return to the track, which was barely a 10 minute journey. Due to the amount of traffic. Afterwards I decided to walk back to Misano Adriatico which was mainly downhill and approximately 30 minutes walk. Got the train back to Rimini, Easy.
Sunday
Arrived at the train station, only to find out that most of the trains had been cancelled due to engineering work! No trains coming for more than an hour, so most people decided to try the bus 124 for 1.5 euros, as there is a ticket office right outside the station. After waiting 1.5 hours, the bus finally turned up, everybody breathed a sigh of relief. A couple of miles down the road, the bus pulled over and the driver got out! It had broken down! A few of us decided to walk to Rimini Miramare station, which was about a mile away, to try our luck. When we got there, there weren't any trains (surprise, surprise) but, there was a tram, which took us to Riccione, from there we got a taxi to the track which cost 30 euros. Once again, after the racing, I decided to walk back to Misano Adriatico station, where I managed to get a train back to Rimini. Definitely a day to remember!
Apparently, there were shuttle busses running from Cattolica, but I didn't see any in Rimini, Riccione or Misano. I'm sure I'll go again but will stay in Misano or Riccione, as they're nearer the circuit.
When using the Trenitalia app you need to check in (verify) your ticket before travel, and on the busses there is a machine on board to do this.
All in all, it was a really good weekend and will definitely go back.