You may not use your garden furniture all the time. Especially in the UK. Although when it is sunny it is great to have garden furniture that is fit for purpose and that you can accommodate with your budget. The next question on your mind will be something along the lines of what material should you buy, how simple are the to construct, maintain and ultimately how durable they are going to be.
When picking your garden furniture would be thinking about what is the purpose of it. Do you want to relax, eat or entertain in that space and do you have enough space in order to do those things. You will need to think about the current style of your abode as well as the theme to your furnishings in general.
Once you have determined your style you need to consider how comfortable the furniture actually is and what protection can you get from the elements to ensure they are more of a long term investment as opposed to a seasonal disposable expenditure.