Removing Bath Drain Collar but not Sure What Correct Tool is Called Drainage and wastage systems and plumbing help, advice and answers

[drmandarin]

I need to remove the bath drain collar so that I can fix a leak.
Usually I would use a tool like this to unscrew the drain collar:

tool image

But I have no idea where to source such a thing in the UK or what it might be called here. Any pointers please?