Having just completed a History PGCE myself, I wouldn't lie and say it has been an easy year. History and Maths are so different that I think that trying to learn and practise the different pedagogies at the same time would probably be extremely difficult! I suggest the same as what other posters here have said - if you think teaching Maths is a better career option then you should opt for teaching Maths instead (the competition for places are slightly less than say for a non-compulsory subject like History, and you also get more money).
I'm hoping this would make me more employable and with the demand for Maths teacher so high, maybe even help my pay. I have completed Maths up tyo A Level and would interested in Key Stage 3 and Maths.