question regarding cgt, page-5

That is not strictly correct Henster.

I asked my accountant about this previously and as long as you substantiate it with proof, it does not have to be first in first out for cgt calcs.

Here is also something I found just now for Vanguard funds about the CGT calculations for Vanguard units:

The FIFO method is a way of matching units you have
disposed of with units you purchased. It assumes that the
first units you purchased are the first to be disposed of. You
are not obliged to use the FIFO method when calculating
capital gains. However, the CGT Statement is based on this
method, and if you choose not to use FIFO you will not be
able to use the calculations provided by Vanguard in the CGT
Statement for this or any future year. If you choose to use a
method other than FIFO, you will need to maintain your own
records relating to the cost base of your units.

Cheers.