Just wanted to say thankyou to everyone who commented on my post here healthunlocked.com/thyroidu...
On the advice of a number of people, I made an earlier appointment with a different GP who immediately diagnosed hypothyroidism and has started me off on 25micrograms of levothyroxine. I've been given another four week fit note to work half my normal hours, and I'm hoping that once I've been on the levothyroxine a month, I will start to feel more like myself and be able to go back up to my normal 28 hours a week.
I didn't manage to get a referral for possible secondary hypothyroid and nor did I get more blood tests for B12 or folate, I just didn't feel like I could ask for any more once the GP had actually said he thought I had hypothyroidism. I'm going to look at supplementation for my low ferritin levels (28 ug/L (normal range 11-307))
I have an appointment for further blood tests in 6 weeks and another appointment with the same GP the week after.
So anyway, thanks again to everyone for your help, I will let you know how it goes!