Hi BLH666
Welcome to these Forums.
I honestly doubt that in this social media age, you are going to open many doors with flyers.
I am guessing from what you have written that your background is in construction but that doesn't tell the readers here whether you experience has been in designing and/or constructing (constructing in the widest sens of the term as in CDM) structures, as an H&S professional in the sector or perhaps a mix of both.
You can in broad terms split Contractors into three groups:
1. Those who generally know what they are doing and usually employ an in house H&S etc professional resource.
2. Those that don't really care and if the accident happens, even if that results in prosecution probably won't change their ways. The very small chance of being prosecuted is just one of the risks of doing business, not dissimilar to choosing not to pay for parking and occasionally being hit with a Fixed Penalty Notice.
3. The ones in the middle who are not that sure how to progress and who might be looking for help from one or more external consultants.
You are going to be wasting time and money if you start leafleting those in groups 1 and 2.
So you need to try and work out which Contractors are in group 2 and consider how best to get your foot in the door. Word of mouth recommdation is much more likely to be fruitful than a leaflet through the door.
AND very similar considerations would apply to the Clients and Architects (and other Designers) except perhaps more so as they seem to have been a protected species from very soon after the first iteration of CDM came into force.
If you look at the HSE databases for prosecutions and notices and home in on CDM (as it is much more difficult to analyse than e.g. HSWA) then you will find that prosecutions and notices against the front end CDM duty holders have been VERY, VERY rare events for nearly 30 YEARS! [OK, the databases don't go that far back, but the overall pattern has been largely the same, with the trend, if any, being LESS enforcement against the front end CDM duty holders].
In the run up to CDM Mark I, I was working for a large multidisciplinary consultancy so we put on a road show to provide CDM training for our own Design etc staff and invited both existing Clients, but also targeted Clients and some Contractors who we thought might wish to turn up.
So some "leafleting" from 1993 except we wrote letters to the relevant people with a glossy flyer for whichever course(s) would be convenitent to the target audience. The grand plan was not so much to sell out H&S consultancy services but to use H&S as a way through to getting a broader range of work from some new Clients. That "leafleting" was almost entirely fruitless except in terms of strengthening EXISTING business relationships.
The advice given to jc pearson from the start of this thread has been sound. I think you need to be much more imaginative in trying to find clients than some leafleting.