Thanks for the reply. After speaking with someone at the garage I use in the UK I was able to complete a temporary repair yesterday, very similar to your photo. There is still a drip but I can improve the repair with better parts. I will post a photo.
I am now close to being able to drive again, admittedly short distances and with extreme caution but this is a big step forward so thanks to you and others for the help!
One question: when the housing arrives, can I reasonably expect to be able to unscrew the new valve and simply insert it into the old housing? Will it be obvious where it is meant to sit, what I've read refers to feeling strong resistance? How confident should I be that it is definitely the valve that's the issue rather than anything inside the housing i.e. the bore where the valve goes in?

