In a situation where there might be about 8 checkers left to bear off, with gaps, what is a simple way to estimate the number of rolls needed ?

I am hoping to find a 'Simple' solution as I am quite new to counting.

Why don't you post a typical example? That would make the discussion much easier. There's no general answer to the question you posed.

This is not a position I would do as a rolls vs. rolls estimate on. I assume you were looking for ways to convert the checkers into a 4 rolls versus 4 rolls or a 3 rolls versus 3 rolls for cube decisions.

However, there are other estimated pip count adjustment systems available like the Keith count, Isight, or Walter Trice's count system to help determine cube decisions for positions like this.

For example assuming you and your opponent have the same number of checkers, and your opponent has at least one checker on the 4 point, 5 and 6 point and the cube is centered. I would do an adjustment for this count as I would do it in game.

Your direct pip count is 28 pips. You have a penalty of 2 pips here (a penalty of 1 for more than 2 checkers on the 2 pt. and a penalty of 1 for the gap on the 4 pt.) Your adjusted pip count is 30.

Then I would make the adjustments to my opponent's position and I would double if his pip count is 30 or higher for this position. (I am using Walter Trice's formula for short races here. [(n - 5)/7 for the point of last take and doubling if your opponent is within 3 of that point. 30 - 5 = 25. 25/7 is 3 (+ remainder, but you drop the remainder). So according to the formula your opponent's point of last take is 33. You have a double at 30 and a redouble at 31 pips in adjusted counts.

I would highly recommend Walter Trice's book Backgammon Bootcamp for this topic. He has a whole section of the book devoted to racing cubes with all of his pip count adjustments and formulas fully, clearly and comprehensively explained.

(among other things, it is one of the best Backgammon books)