Ty-rap guns can be found on ebay, try the AlienSpirit aviation tool supply shop. They will ship to the UK, but beware customs import fees.
Snap on tools are good but expensive. As Aveng states, the ratchets are second to none. The ratchet screwdrivers are also the best. For a little less cash, I find Facom nearly as good, also with lifetime warranty. It really depends on how much you want to splash out. US Pro make some half decent and cheap spanners. Craftsman tools are also worth a look if you are planning a trip to the States any time soon. These can also be found on ebay, there is someone selling various Craftsman tools on there, from their location I'm guessing all sourced from one of the US Air Force bases in their area.
Lots on
http://www.airmech.co.uk on this subject.
Good luck with the contracting.