Welcome Adam, well done for chosing the loopies and friendliest thread to chat on!
If this is your first race, then I'd suggest not worrying about the time too much; with a 55 min 10k you certainly have the potential to run a marathon in some time between 4:30 and 5 hours, and if you're able to plod 14 or 16 miles at this stage, you're not doing badly at all.
See if you canup your midweek mileage a bit too, so your LSR (long slow run) is less than half the weekly total. Even with 3 runs a week, that's not too difficult, as you could do a 14 and two 7s to make 28 miles per week. Once into February, I'd suggest 30 a week at least, but keep each week in February about the same, then in Marhc, keep the midweek runs abot the same and step up to 35-40 by increasing the LSRs towards 20 miles.
Don't increase weekly mileage by more than about 10% (so 20 can become 22, 25 can become 27.5, etc. and don't increase each week's LSR by too much at a time too. Every 4 weeks, drop the mileage a bit (by 5 or 10) and do some speedwork (perhaps another 10k race) so blow the cobwebs off!
Most importantly, enjoy it!
