At the moment our network consists of a BB modem connect to a wired router, then 1 cable from that to my machine, and another to a switch in a different room which has 4 more machines on that. We need to get wireless now (not to use for the machines, but to test out cards - my dad is a pc engineer). We have been looking at getting a wireless access point and plugging that into the switch, although a wireless router is actually cheaper than the access point! My question is, would it be possible to buy this router and plug it into the switch and use it just as an access point, ie disabling the DHCP settings etc. This would also come in handy in case our main router fails in the future. So basically, would a wireless router work as an access point?

Yes. If you are only testing you can leave the DHCP on.