As Jay says, to change your name on your passport you just need to include your deed poll. To change you gender, you need a letter from your doctor saying that you're transitioning from Female to Male and that it's a permanent change. I can give you a link to a sample letter if you want one. You don't need to have started any treatment, and you can get the letter from your GP, so if they're willing to write the letter for you, you might be in luck.
Failing that, I'd suggest holding off on renewing your passport until you can get a letter from your GP - else you'll end up having to pay the £77.50 fee twice - once to change your name and then a second time to change your gender marker. Of course, if you're planning to travel before that then I guess you don't really have an option.