Man you guys are the best, thanks for such useful responses!
I have a 3/8" torque wrench, so I have purchased the park tool BBT2 - thank you so much dsbrantjr for the detailed response.
dabac - From the specs on the bike, I believe I have the widths/lengths you mentioned (68mm x 118mm). I will see how I get on with this tool and cleaning/tightening the existing bottom bracket, and if I get no joy I might post back here to double check the new one I order should it come to that.
Thanks again both of you!