Hi. My name is*****'m looking at your question now and will post my answer or ask for more information here in a short while.
Can you rephrase your question please. I'm not entirely sure what you are getting at.
Any gains you make on shares held in an ISA are completely tax free regardless of the level of the gain. Income earned in an ISA, eg dividends, is also tax free.
I hope this helps but let me know if you have any further questions.
If you put £10K into an ISA in one tax year, you cannot carry forward the unused £5K to the next tax year.
You are limited to £15K investment per tax year. The gains you make aren't part of the £15K allowance.
I did answer the question. All gains and all income made inside an ISA are tax free. That's the whole point of an ISA. Look here for confirmation.