Hi, had the same issues here. The part you are looking for is the CR-1220/FCN, the leg configuration on the Farnell one is VCN and needs bending but some consider it a "modification" so will not approve it.
I have found some in Europe but I am currently trying to get a friendly battery supplier in the UK to give me details and prices, If they can do it I have asked them to post on here, if they are not allowed as it is "advertising" then I will.
The price mark up on these batteries is obscene, I have sourced them in the US at just over a dollar but they will not air freight. Alibaba do them for 7 cents US with 50 as a min order, but not sure about shipping from China.
I will keep you posted on my efforts.