The amount of existing 'beyond rubbish' CCTV outfits operating from 15 year old hatchbacks, selling SWANN kit at £199 'fully' fitted for a 4 camera system would suggest against the need for licencing...
Welcome to the site but this does seem to be a bit 'cart before horse'. There is plenty of info out there on what SIA does and doesn't regulate.
Do you already have a good deal of business (i.e b2b, not domestic) contacts who already use security services of that nature? (Assuming the current customers of, say, a trade counter would
suddenly start buying CCTV and the like isn't going to work).
If not, I would seriously rethink your business unless you hate your current job so much, anything would be preferable (but if you have a mortgage / kids, I'd still think again)
You would be better of in virtually ANY other trade, income wise.
I have just done a job in a million pound house where; whilst it was a good job for me as intruder goes, I was working alongside...
A plumber who charged £100 for a 20 minute repair
A (crap, the worst I've ever seen, my woodworking is 200% better) joiner who charged £300 for a day of 'door adjustments'. This mainly seemed to consist of spraying WD40 and padding out the occasional hinge with old Navy Cut packets he pulled out from under the floorboards I had taken up. Oh yeah, and whilst I had to do my usual act of eating a sandwich with one hand whilst fixing down the trunking lid with another, our joiner friend 'went off to get some bits' around 12. As it's in the middle of nowhere, and he was gone for barely 40 minutes, I strongly suspect he actually went to get a nice cool lemonade in the Blue Lion...