If you are hypertensive it is important to keep your BP well controlled before pregnancy. Unfortunately chronic hypertension carries a 25% risk of developing superimposed preeclampsia during pregnancy, so know the signs and symptoms of preeclampsia: http://www.preeclampsia.org/ There are also some experienced ladies on their message board that are also on BP meds if you want more advice.
Methyldopa is one of the safest BP drugs for pregnancy. It's older and there is a lot of data on its use. However, I didn't like how I felt on it and it didn't control my BP as well (dose would wear off quickly).
Labetalol is another drug commonly used for pregnancy, but I wanted to avoid beta blockers since they inhibit thyroid hormone conversion and I'm already on meds for low thyroid.
My cardiologist said he has had a lot of patients on calcium channel blockers during pregnancy, so I'm on procardia right now at 34 weeks gestation. Baby is doing great.
I would definitely stop smoking if you can since it can not only raise your BP it is also can negatively impact pregnancy. (preterm labor, low birth weight, etc http://www.marchofdimes.com/pregnancy/alcohol_smoking.html).
Since you are getting older and risks go up due to "advanced maternal age" I would ask your doc if it would be better to loose weight before ttc or if it would be better to ttc while you are younger. Loosing weight only lowers pregnancy risks slightly so it wouldn't be my highest priority right now.
If you want more information on your risks or what the best treatment plan for pregnancy is you can always ask your OB or GP to refer you to a MFM specializing in high risk pregnancies for a pre-conception consultation. They have a lot more experience with hypertensive pregnancies. http://www.smfm.org/default.cfm
I hope this helps, good luck with whatever you decide!