Take a look at http://www.ladderexchange.org.uk/index.html which is offering companies the chance to exchange 'dodgy old' ladders for discounted new ones. The site also has a list of ladder companies - most of which have the type of equipment you are looking for on their website. I'll also send you a PM about our Good to Go Safety ladder tag and checklist systems which might be of interest.

The feet of a ladder usually have a very limited area in contact with the surfaces on which they are placed. Therefore, if a ladder is placed on any surface which is relatively smooth, there is a foreseeable risk that its lower end can suddenly slide away backwards while in use. The ladder user is effectively subject to an unexpected fall even if he/she hangs onto the ladder, and may well sustain serious injuries. Therefore, if it’s not practicable for the ladder to be tied in position (preferably at the top) it’s worth using a stopper device under the ladder in order to resist the tendency of its feet to slide. In contrast to a ladder foot a stopper device has a considerable base area in contact with the floor. This factor plus the applied weight of a ladder (and its user) usually gives a stopper an excellent grip on floors. There are different makes of proprietary stopper available, including ones which can be adjusted to allow them to be used on sideways sloping ground. Decades ago I made an improvised stopper for home DIY use consisting of a short length of plank with a batten screwed along its upper centre, and it seemed to be reasonably effective. Even so, during the 1990s, I replaced it with a proprietary aluminium one, partly because its rugged rubber base probably had better grip than wood and partly because it wouldn’t absorb rainwater. With a name which sounds like Kojak, the device was relatively new at the time and had received good reviews from users and others. There’s plenty of information about stopper devices and various other ladder safety devices and accessories available by searching the internet using terms such as ladder stopper and ladder safety. As with safety for many activities and situations, don’t just rely on having appropriate and effective equipment. It needs to be complemented by having users who are suitably trained and, among other aspects, know the limitations of the equipment. For example, ladder users need to know that ladders should be used at an angle of about 76 degrees (alias a gradient of 4 in 1) for optimum stability and also to avoid straining their stiles (the long bits supporting the rungs).