Hi Mark,
I faced the same problem earlier in the year. I read a few posts about damage to the oil filter housing gasket by stressing the filter housing when changing the filter DIY style, so I bought the aluminium tool from a BMW dealer, to make sure it fitted well, and being lazy, rather than getting online. It was £12, eBay had plenty listed nearer the £8 mark. Aliveankikin's advice will get you what you need. At the time I just wanted the info from the dealer parts person, when he quoted the price I figured, why not?
Probably overkill, but I bought a torque wrench to make sure the lid was torqued properly, without stressing the filter housing, and easy to undo come the next change. I also used the torque wrench on the sump bolt. I wanted one anyway though. Both torqued to 25 Nm I believe.
Are you dropping the oil? If so I can share that try and have the car front end level, or Jack from passenger side (UK RHD - is yours LHD?), jacking driver's side for access leads to oil dripping into the undertray when the flow reduces during draining.