Great article ! Based on my experience and the advice of expert Steemians, your article shouldn't be long as long as you have a user base that will be reading your articles in the daily basis. My third article was long and too comprehensive for my readers. As a result, I broke down the entire article into three articles. You'll save time at the end.
Another cool topic that you could implement in your article, is how to save money with transactions when buying cryptos. Always, check the transaction cost on this page before buying. You can avoid large mining fees like this.
Here's the website: https://bitinfocharts.com/comparison/bitcoin-transactionfees.html
RE: How to buy Bitcoin in the UK