CGT Advice On Long Term ETFs

Afternoon all. First time posting as I am trying my best to gain some savings for the long term and wanted to understand how the capital gains tax and any other taxes, I need to consider if I want to invest in ETFs. I just want to know what I must do so I abide by the law. Currently I am thinking of having a portfolio of 4x ETFs (2x ETFs will be Acc and 2x ETFs will be income). I currently work as well full time and pay into our company pension scheme. All 4 ETFs will be kept for a long time (20+ years) and at the end will likely be selling them when I retire. From what I understand (please correct me if I am wrong) I do not pay any CGT until I sell my ETF’s. However, if I for some crazy reason I want to sell my ETF early and I have gained more than my allowance I would need to fill a self-assessment form? If I do consider selling them and making far less then my allowance, do I still need to tell HMRC by filling in a self-assessment form about my profits? But when it comes to the income ETF’s will this be taxable once I earn a certain amount of profits a year? Is this the same as the CGT or is this classed as Dividends Tax instead? I know the allowance for this is much less, but I doubt I will get much for a long time. I was planning in the future to appoint an accountant to do the taxes for me once I decide to sell everything. Is this a better way to handle this or should I get an accountant now to monitor it and fill in a self-assessment every year? Apologise if these are simple questions but I have tried my best to research and gather up all the information I can. Many thanks for your assistance and I wish you all good fortune!

Hi Shiv Patel,
HMRC cannot comment on future events as legislation and/or plans may change.
For current guidance please refer to:
Report and pay your Capital Gains Tax
Thank you.