Dean
If you are looking for an add on then you need to get a hotbox for your pressure washer and then this will give you the option to do chewing gum removal. Try Britclean at Biddulph, I think mine cost about £700 - £800.00.
As has been said you need to cordon off a large area if working through the day or limit the works to night time.
The other option is to get a dry steam machine, like the one Dave has offered, they are the ones I have and both methods have their place.
I cleaned a store front in Balham - London, I could only use the dry steam machine, whereas ordinarily we would just pressure wash store fronts and include chewing gum in the course of cleaning, no pedestrians for this though.
Just because you see it everywhere don't presume you will get lots of work. In law raised chewing gum is classed as a litter and must be removed within 2 years, once it is flattened it no longer becomes litter!!!
Good luck
Rob
