I've been a blood donor for a long time. I agree with you and I've made the same comment. When I first started going you could just turn up to a session and queue, but now they expect you to make an appointment online. The sessions get booked up weeks or months in advance which I am sure must put some people off. I usually try to get a cancellation appointment by checking the website regularly. Also they have scrapped their mobile vans so most sessions are held in church halls. For information the nearest locations to SE22 are Rye Lane chapel, The salvation army training centre at Denmark Hill and St. Faiths church hall Dulwich. There are many other places if you don't mind travelling. If you work in the West End, there is a permanent centre near Oxford Street which is open 6 days a week and it's very easy to get an appointment, but I appreciate this isn't likely to be convenient for most people in SE22. However do please try to give blood if you are able.