Back about 10 years ago when I had an episode, the standard first line of treatment was "block and replace" - carbimazole to block the action of your thyroid, then once your hormone levels had dropped, thyroxine to replace the missing thyroid hormones. Effectively, they give your thyroid a rest for 6 months to a year. The reason for doing this is (in the absence of antibodies suggesting it's an autoimmune problem), in about 50% of cases, it spontaneously clears up when you come off the drugs and you need no further treatment (which was, luckily, the case for me). My grandmother had her thyroid out too - I don't think that has a bearing on whether you have the type that will clear up given treatment or not.
It will depend on your GP - I had to have quite a few blood tests as they have to tweak the drugs till they get the levels right, but my surgery was quite good about giving me morning appointments before work. I did however feel completely knackered until the drugs started working.
But fingers crossed - it is treatable, and in most cases will have a good outcome, and there's an evens chance it will clear up after treatment, and you won't need anything more. If block and replace doesn't work, the preferred treatment is to try radioactive iodine to destroy part, but not all, of your thyroid's natural activity - this can leave you with an underactive thyroid and dependent on thyroxine. But you have options - you can opt for surgery (not often done these days) or further courses of block and replace.
Good luck with it - and if you can take any time off work, and your doctor offers to sign you off, I'd take them up on it (in retrospect, given how crap I felt, I regret dragging myself into work when I was actually quite ill - but I'd got to the palpitations/visual disturbances/continual sweats and breathlessness stage, because I stupidly put off going to the doctor, doing my "strong silent type" act until my mum kicked my arse).