How can I convert a value in the form of HH:MM:SS.111 to just seconds?

As well Im still trying another work around, and if it works ill post my solution. But it consists of me splitting up the hh:mm:ss.111 splitting them up into separate columns using the "Text to column" tool.

However the "Delimitated" function is not separating the hh:mm:ss.111 into columns. I suspect because it can not see the colons. The colons are being placed in the cell due how the cell is being formatted and have not actually been typed in to the fx box i.e. colons are not displayed in the top fx box, so 15:30:10.111 in a cell displays in the top fx box as just 153010111 so the delimitated function can not separate as it can not see the colons.

So I am having to use the "Fixed Width" tool instead. But I am encountering a problem as 0:00:00.111 in the fx box is shown as 111 and not 00000111 (I need it to stay as 00000111 in the fx box and not 111) .

So how can i get excel to recognise and keep zeroes, instead of deleting the zeros from the fx box if a figure starts with a bunch of zeros?