Hi,
The British thyroid foundation shared this today:
https://www.gov.uk/government/news/teva-levothyroxine-tablets-re-entry-to-market-and-introduction-of-new-tablet-strengths
TEVA's licence to produce thyroxine was withdrawn in 2011/12 as it wasn't being produced to the strength it was supposed to be (caused a right royal fuck up during my pregnancy 
and I wasn't very well) -
However, they are back on the scene and with a new strength of tablet too, 12.5.
I think this is important to note as often doses can be tweaked like this to reach the best control of symptoms. I used to be on an alternate day dose of 125/150 (pre pregnancy and in fact on teva) and now mostly 125 with an extra 25 twice a week. This adjustment made a huge difference to me. But does need to be done making sure tablets are taken correctly every day (as much as possible) to get the right level.
ALSO this could be a potential dose option/ tweak if you are borderline and the GP does agree to trial thyroxine (e.g. If planning pregnancy and tsh is around 3-4)
I also want to say I know some people use combo t3/t4 - this is not a discussion about that. However it is always worth adjusting your dose in a fine tuning way and trialling it for a good 3 months to really see how your symptoms are before going down routes like that, as well as checking other potential issues that might cause similar symptoms e.g. Vit D, B12 and ferritin (best over 70).