Hello. I had horrific sickness and ended up working from home for a month as I couldn't get in the car without puking. I think I started to feel bit like normal from about 22-23 weeks so it was a long haul but, I think a lot of women do feel better before that.
I am not up to date with laws as am expat but I am pretty sure pregnancy related sickness does not count towards your usual sick leave, so try not to worry about it. I found stress made the sickness worse, so try not to worry, ditto not eating, try small bland snacks like slices of plain toast, crisps. My doc suggested fizzy water as tap water made me puke, and that helped stave off dehydration.
I am now 37 weeks and still get a tiny bit of nausea from time to time but that's from the baby squishing my stomach I think. My doc put me on premosan as navidoxine turned me into a zombie and didn't really do much for the sickness, the premosan did seem to help. It is awful at the time as everyone keeps telling you it should be over by now because people seem to think the puking magically stops at 12 weeks, which it does for some but not everyone. Just keep trying different drinks and snacks, and try not to kill the people that harp on about bloody ginger! (That drove me nuts as the smell made me sick). Oh and forget housework, if you've got someone to help you great, if not just do the bare minimum to stop the rats from moving in and get to work when you can, but if not rest and look after yourself. My doc was really nice and said don't worry, if you get really dehydrated we can give you a drip to sort your fluids out.
Once I worked out things I could eat and drink - small amounts of pasta, plain cheese sandwiches, lemon Melissa tea by Lipton, Rachel's organic my first yoghurts (they're for toddlers but so what? Eat what works) then it was still pretty miserable but bearable.
The hardest thing for me was that this is my first so I had no concept of what it would be like. I think I expected to be a bit sick but mainly carry on as normal but I was basically floored by it. I really do think that the Kate Middleton puke fest helped as it raised awareness of how bad it can be, that it can actually be serious. It feels like there is no end in sight but there is, I promise!