I would wait until April to renew with your married name.
If you renew now with your maiden name, it will cost a full passport to change to it your married name at a later date.
I didn't bother changing my name on my passport when I got married as I had 7 years left on it and I refused to pay for another one until it ran out. I just booked holidays in my maiden name or if I needed it for ID, I took my marriage cert as well.
My passport runs out next year so will update it to my married name then.