if you look on the web mate. At the various fogger etc. Ask them if they sell the chemicals or solution that go in the foggers.
You can get all sorts for many different things like
Odour control
Ciggerette smoke
Pest control
They are easy to use mate. Its basically turned on by a switch and then it shoots out smoke. Best wear a mask suitable for the application you are using.
They can fill a room / house in several minutes.
No you shouldnt need to use a fogger then do a major clean. The idea of them is to save time and labour.
If you are totally new to it buy one, get some chemical for odour etc and do a test in your own home. Or even a freinds Home. You can even use then in cars to get rid of cigerette smell etc.
I would invest in only a small one of about £200 mark max if you do not have the business telephone ringing. However like you say if you get alot of EOT cleans that have odours then they are ideal.
I hope this is of some help.
Also heres another link,
http://www.fog-it.co.uk/packages.htmOh and for pesticides you need to go on a course but could offer odour control. You could offer DIY pestiised products.
Dave
Dave