Open Ltd company from start, won't cost much over the year
nsi or saaib only if you want to do urn's, ssaib being easier to get , as suggested by others you need a buddy company for call out, or a buddy company to accept your installs and take the maintenance on for ones that need a urn, I seen a few doing that here
Redcare less demand? Webway etc all easy to set up
Yes money is the whole point, but you will find it difficult as a house basher lol, but it's the urn side that gets you stuck otherwise plenty will take maintenance on with keyholder only and as above buddy to take your urn requests but you need a good mate for that
Anyhow alarm men will be here soon with better advise