Hi all. We are glad to report that we all survived this journey. For those who expressed an interest in the route, here are the details.
Firstly animals. We took 2 GNV ferries. The first from Barcelona (the Tenacia) had appalling conditions for pets. Basically, accomodation was a wooden box on legs, screwed to the floor of the top deck at the back of the boat and available for all passengers to walk up to. There isn't much protection from the elements either once at sea. We ended up fixing towels over the wire front as it was wet and windy overnight. The second ferry from Genoa (the Splendid) was better in that cages were inside with some ventilation and light. They are on the small side if you have 2 larger dogs who want to stay together. There is a separate room for smaller animals but those cages are tiny. We ended up putting our cats in the dogs room, so we could fit in their carry case and a litter tray. If you want to take this route with pets, my advice is to check which boat is running.
If you are travelling from Genoa, it's best to get there early (or very last minute to avoid the queues at check in!). We were directed to the far end of the port, away from the nice shopping centre, so the next tip is to stock up on any food and drink before going quayside (like we should have done!). You have to go to a terminal building to check in and to complete a landing card for Tunis (even if you do not disembark there). All cars bound for Malta are stored in a corner of a higher car deck so they don't get in the way of those leaving at Tunis. Good parking skills are a prerequisite...
The ferry itself is a bit dirty and shabby, as pointed out in earlier threads and half the facilities are not open. We were looking forward to a relaxing evening after travelling for 3 days, with a nice meal and a glass of wine. The restaurant was not open at all during the voyage. The cafeteria was only open for an hour or so 3 times a day. By the time we had unloaded and settled the animals and had a shower after boarding, it was closed! There is a bar that is open 24/7 and serves pizza slices, pastries and ciabattas and a small shop that opens for a couple of hours a day. All other facilities were shut. When other passengers complained at the lack of facilities and the general condition of the boat, the reason given was the "clientele" on that particular route.....
Final point is that the boat apparently never arrives in Malta on time (advertised as 8.30am - we finally docked at 2pm), so don't make any plans for that day.
This does read like a lot of negatives, but for us, the convenience of not having to drive through Italy and Sicily - especially having driven from Marbella to Barcelona with 2 cars, 2 dogs and 2 cats - outways these little niggles.
After speaking to some people who regularly do the route, the best way to survive is to book a cabin (we had a standard exterior and it was a very good size), pack a large bag of food and drink (both are extremely expensive on the boat and not that good) and plenty to entertain yourself