This may be a silly question - Ok so I now have £700 invested in bitcoin . Let's say it goes up by £50 - do I remove the profit and leave the working capital( £700 )in bitcoin ? Or do I take the lot?
If I take the lot then when I buy back in It may pay a higher price. What do you suggest?
This is exactly what trading experience will solve for you. I believe that everyone has questions like you but if you only guess about the trend, it is really a gambling game.
To be clear on this, you should really read about the trading documentation and there will be some tricks on resistance and support. It will help you a lot in making decisions.
Without learning, someone can't make a profit unless he always gets lucky in the trading. When we can learn from many tutorials, we will have the skills to analyze the chart which will help us to get the right price to buy, although we need more practice to get a higher chance. If you can practice every day, then I guess it will no need to a long time to improve your skills because you get the experience with practicing trading.
You should also know that the market will not have the same pattern in every day, so you need always to analyze it before you decide. If you can see the price start increase, then that is the time for you to prepare in the sell order and place your price to sell.