Good luck today BishB! Your team will hopefully talk you through the most likely side effects and give you drugs to counteract them. Also you should be given a number to call if you have any problems.
I didn't love chemo but I was never sad, tired though definitely! Spent each session with a manic grin on my face 
it was actually rather embarrassing as I couldn't stop it 
but chemo wasn't so bad, the nurses were so kind and each one was one closer to the end. I found it frustrating and so boring being ill during each cycle though, and that the tablets would finally be out of my system and I'd feel at my best on the day of the next infusion.
Take some activities to do (books, magazines, things you can one handed). I tried to knit but had to stop as it was moving my cannula and slowing the infusion. I think crochet would probably have been okay though. Also could take cards if someone will be with you. But bear in mind you might not feel like doing anything. The steroids made me very restless and I couldn't focus on anything for very long.
It doesn't seem like it now I'm sure but the sessions will fly by. It seemed like only a month and suddenly I'd had all eight cycles.
I hope the portacath doesn't hurt too much and that all goes smoothly.
Also try and keep a symptom diary. Just a note each day of what symptoms you had. They might give you one but I found it wasn't that derailed. It feels a bit gloomy but will be useful as you may forget symptoms by the time you next see your oncologist and also because after a cycle or two it will give you an idea of your likely best and worst days so you can plan accordingly.
If the anxiety continues, your oncologist or GP may be able to prescribe you something, as you shouldn't have to feel that awful 
hopefully the known will be a lot less scary than the unknown, even if it's still a bit shit.
Anyway I've rambled on enough. All the best for today 