If you can keep the other gains down in 2013/14, then there really is no point in doing all the work required to work out the gain on each individual payment received from Rolls-Royce and Santander.
The payments from Santander total £3,109 so if you deducted that from the probate value, it would make any gain on the final sale £3,109 higher. Given that the shares were finally sold in the 2013/14 tax year (is the date 24/2/13 a typing error?) the gain would be £6,895 (£29,816 - £26,030 + £3,109). The cost of the additional 135 shares would need to be deducted from the £3,786.
The same principle would apply to the Rolls-Royce shares. The gain would be £589 (£4,414 - £3,986 + £161).
The fact that most of the individual payments and the final disposals occurred in the same tax year, 2013/14, means that the botXXXXX XXXXXne gain figure will be the same whichever method (the less than 5% method or the actual calculation per receipt method) is used to do the calculations in any event.
I have alot of experience of dealing with CGT on shares in general including sales of rights etc and I've dealt with many Santander share holding clients so I know what needs to be done but without the paperwork its very difficult, time consuming and, in this case, academic for the reason given in the previous paragraph. I doubt you will find anybody else here willing to take it on as there is alot of work involved but I'm willing to opt out so another expert can take a look if you wish me to. Let me know either way.