I dont know the cause of your high bp so I cant really answer that. If you have health issues you should consult a doc before fasting. First things first is to clean up your diet before starting fasting. It makes the fasting easier to deal with and is easier on your body. When you start fasting you should always start out with short fasts to see how your body reacts. Some body's cant fast at all.
I second the mention of trying juice fasts first and agree with starting on The Master Cleanser . Free book online:
healthandlight.com/TheMasterCleanse.pdf
Detox can be like the flu at times. So if you really want to avoid that for this year look into detoxing/weightloss with the "raw food" way. Just google "raw food"
You will find tons of info.