Based on my experiences over the last few years you could get from Upton to Sharpness in a day if you started off by mid morning at the lastest.
You then have to wait at Sharpness for the tide.
It will then take a couple of hours or so to get to Portishead depending on your speed (you will be assisted by the tide).
You can either anchor up or go into Portsihead Marina for a short stay at a reduced price.
You then have to wait for a few hours for the start of the next tide that will take you up to Bristol.
In summary:
You cannot do Sharpness to Bristol on the same tide.
There is only one lock out from Sharpness at each high tide.
Bristol City lock will only be open just before high water each tide.
However things may have changed lately as there are normally restrictions on all the openings of the swing bridges on the Gloucester & Sharpness Canal. You also may have to book ahead.
Also the river locks and canal swing bridges might not open on certain weekdays out of season.
I have in the past done Stourport to Sharpness in one day.
Worcester is approx 1 hour up river from Upton
I forgot to mention... you will also need a temporary 'canal' licence once you get to Gloucester. However your 'river' licence should allow you to avoid paying the lockout charge at Sharpness.