Hello Stera, hope you're ok.

We use cheap bleach to clean our patio/slabs. Water it down in the watering can and apply through the can rose. Kills moss and green algae quickly and effortlessly.

Steragram. Personally I have a B and Q own make. High Performance is the brand name of it. I've had it 6 or 7 years without problems. It is probably only used around 10 times in the year. It is reasonably lightweight too.

I use a solution of Armillatox Moss & Outdoor patio cleaner, I just apply it over night and dont need to do anything else.
We have a hose pipe ban here you might need to check if you do or are about to have a ban?

The problem with using a chemical option is that any run off from the patio will run straight down onto the beds so bleach is a non starter in the back garden, though in the front it would be OK. Would the Armillatox be OK running off onto plants?
Thanks for the tip re B&Q. We don't have one locally but it might be worth an hour's drive . Our only large DIY is Homebase.

Thank you all for your very helpful replies - much appreciated.

Steragram - try out this site for info.
Didn't have much time to look at the whole site but you may get some good info....
http://www.pressurewashercleaner.co.uk/

Armillatox is an environmentally friendly herbicide/fungicide 100% bio-degradable, Non-polluting, naturally occuring ingredients and is a vegetable oil soap based product

Wow. What did I do before I got to know you lot? Thanks very much everyone. I do like the idea of applying it and doing nothing else, sounds like my sort of thing. Stiill need the washer for the walls though, so will also look at the site you mention Scottish.

Good luck with whatever you choose :)

Thanks! Looked at the site, more bemused than ever! :))

Oh dear!!!! I did mean to help lol!!

You did, Scottish, you did!