I have a 1.4 manual and brimmed with £55 of fuel it gets about 365 but I know I could get more if I drove more conservatively.
My mum has a 1.2 manual, so I'll ask her what sort of mileage hers gets for you, pretty sure you should get more than that.
How much does a "full tank" constitute money-wise? I'm pretty sure my old 1.3 K11 had a broken fuel gauge as it would go from the red to full with £30, and I'd get 250 miles out of it. However when we drained it, it said it was 3/4 and yet filled the bigger tank in my K12 from empty to full and then put half a tank in my mums car too. So I think it had way more than empty when it hit the red. Try and work out what MPG you should be getting, it should be over 40 easily.