I think that is a possible combination. If that's what you want to do then you should try it out, and then you can reevaluate when you get to second year.
In regard to workload, I would echo what someone else said. Consider droppping one of your other subjects and doing a full further maths, if you're interested in that, as further maths is easier than other subjects in terms of workload.
well it dint do me any harm in my uni application. ive got offers from Nottingham, Newcastle, Leeds, Birmingham and UEA for History V100. cant be that bad a subject then can it...